Over the course of nine seasons and 180 episodes, Seinfeld became one of the shows that defined the 1990s. It also left an indelible mark on television comedy in the wake of its controversial finale in May of 1998. Created by Jerry Seinfeld and Larry David, and based on a fictionalized version of the former, Seinfeld was deliberately a show about nothing. Still, its focus on the superficial and mundane never stopped it from asking the questions that really matter, like: Can a person die from an odor? What makes someone sponge-worthy? And can we have soup? (The answers: Don’t be ridiculous, it’s complicated, and no, no soup for you).

Co-starring Julia Louis-Dreyfus as Jerry’s ex-girlfriend turned co-complainer Elaine Benes, Jason Alexander as his embittered bestie George Costanza, and Michael Richards as his oddball neighbor Cosmo Kramer, this iconic cast of four led us through some of the most outrageous and hilarious scenarios to play out on screen. Sadly, since Seinfeld has been off the air for decades now, we’ve lost a number of Jerry and company’s old friends and nemeses in real life. Don’t you just hate being out of the loop? Here are the Seinfeld actors you may not know passed away.

Ruthie Cohen

In many ways, Monk’s Cafe in Seinfeld is as much a character as the actors on screen, and its human embodiment is Ruthie Cohen, the cashier who appears in a whopping 101 episodes of the show. Uncredited and unnamed, Ruthie might not always get a speaking line, but during the show’s nine seasons, she appeared in the most episodes besides the core cast of Jerry, Elaine, George, and Kramer.

With her mop of curly hair, sometimes blue uniform, and kindly demeanor, Ruthie is one of the few Seinfeld characters who does no harm to others. Her most memorable episode might be the one where George accuses her of stealing a $20 bill he still had in his own wallet. Actress Ruth Cohen made a career of extra work on shows like The Golden Girls and Murder, She Wrote, with her main success as Seinfeld’s most prolific background star. In 2008, Cohen died of a heart attack at 78.

Jerry Stiller (Frank Costanza)

If we want to understand George Costanza‘s particular damage, we need not look much further than his apoplectic father, Frank, whose impotent rages have been passed down to his dysfunctional and underachieving son. From his obsession with TV Guide to his creation of an alternative December holiday called Festivus that violently combats the cheer of Christmas and Hanukkah, Frank Costanza is almost in a class of his own amid the routine madness of Seinfeld. Frank was such a huge presence in Seinfeld, it’s hard to believe he was only in 24 episodes.

Frank was played by Hollywood royalty Jerry Stiller (father of Ben Stiller), who brought his signature eccentricity to the role with all the gusto he could muster. #DoYouWantAPieceOfMe?! Jerry Stiller passed away in his sleep in May 2020 at the age of 96, having spent the last 60 years of his life making people laugh, from his early appearances on the Ed Sullivan Show to Zoolander.

Barney Martin (Morty Seinfeld)

While Phil Bruns originally played Jerry’s dad, Morty Seinfeld, for his first two appearances on Seinfeld, it’s Barney Martin that Seinfeld fans remember when thinking of the character, since he played him for 19 episodes. George and Frank are clearly related, but the apple has fallen far from the tree with Morty and Jerry; the two have very little in common. That doesn’t stop them from having ridiculous conflicts. Take, for example, the time Jerry bought Morty a Cadillac after a career boost. Instead of enjoying the gift, Morty got impeached as president of the Del Boca Vista Homeowners Association after his neighbors believed he stole their collective funds to afford such a sweet new ride. The enmity between Morty and Frank Costanza was epic, and his brief turn working with Elaine at J. Peterman was as weird as it was funny.

A detective turned actor, Barney Martin died at 82 of cancer in Studio City, California, in 2005. He remains best known for his role as Jerry’s dad on Seinfeld, despite an otherwise storied acting career.

Len Lesser (Uncle Leo)

In a cast filled with literally hundreds of memorable weirdos, Jerry’s Uncle Leo is arguably one of the strangest. Uncle Leo also lives in Manhattan, which gives him 14 wild episodes‘ worth of opportunities to run into Jerry and his friends. Jerry’s relationship with Uncle Leo—a man so pushy that he resorts to grabbing people’s arms while he’s speaking so that they won’t walk away—comes to literally explosive moments, like when one of Jerry’s packages accidentally ends up at Leo’s and blows up. Even after it comes to light that Uncle Leo sparked the conflagration by leaving a can of cleaning spray in his oven, he still blames Jerry.

Played by prolific character actor Len Lesser, who appeared in more than 500 roles during the course of his long career, Uncle Leo became his own force of nature in Seinfeld. In February 2012, Lesser passed away from cancer-related pneumonia in Burbank, California, at the age of 88. Bookstore owners won’t miss shoplifting Uncle Leo, but Seinfeld fans sure do.

Richard Herd (Mr. Wilhelm)

If George Costanza was insufferable even to his best friends, he was exponentially worse at work. From sleeping with his assistants and offering them unauthorized raises to napping under his desk instead of doing his job, George was a nightmare employee. No one was more baffled or unsettled by George’s unruly work behavior than his boss at Yankee Stadium, Mr. Matt Wilhelm. For viewers, Mr. Wilhelm’s puzzled and shocked face over his 11 Seinfeld episodes often mirrored our own as we watched George’s newest antics, amazed that the man somehow never got fired.

In many ways, Mr. Wilhelm feels like one of the show’s few examples of a conscience (until he was kidnapped by a cult), all thanks to Richard Herd’s empathetic portrayal. Herd even made a final appearance in the series finale, along with Mr. Steinbrenner. Herd had been a familiar face in both movies and television until his death in May of 2020 from cancer complications at the age of 87.

Ian Abercrombie (Mr. Pitt)

Wretched though Elaine Benes might be in her personal life, she demonstrates professionalism at work — at least compared to George. Unfortunately, she has to contend with bosses who are all insane to varying degrees. This brilliant comedic reversal makes Elaine one of the more fully rounded of these all-around awful characters. One of the places where we see her struggle the most is in her role as assistant to Justin Pitt, one of Doubleday Publishing’s top executives. Played by British actor Ian Abercrombie, Mr. Pitt’s idiosyncrasies almost put Kramer’s to shame.

From cutting his Snickers bars with utensils and needing a specific kind of white sock that must be ironed before wearing to picking the salt kernels from even the smallest pretzels, Mr. Pitt is one of Elaine’s biggest complaints in more than the seven episodes in which he appears. While Abercrombie was best known as Mr. Pitt, he had a long acting career that began with stage work in the U.K. and ended in Hollywood many decades later. Abercrombie passed away from kidney failure complications in January 2012 at 77 years old.

Sandy Baron (Jack Klompus)

While the majority of Seinfeld takes place inside Jerry’s Manhattan apartment, many of the show’s comedies of errors take place in the Del Boca Vista retirement community in Florida where Jerry’s parents live. Though they’re supposed to be enjoying their golden years and relaxing in the sun, nobody at Del Boca Vista got this memo, and certainly not Jack Klompus, Morty Seinfeld’s main nemesis.

Played by another comedy and Broadway legend, Sandy Baron, for six episodes, Jack Klompus’ general suspicion of the entire Seinfeld family goes to some pretty dark depths, culminating in Klompus accusing Morty of stealing. Klompus also caused an unnecessary row after giving Jerry his special astronaut pen that writes upside down, which Morty insists Jerry needs to give back. Sandy Baron died in February 2001 at the age of 64 after battling emphysema for a number of years.

Warren Frost (Henry Ross)

While Seinfeld was always a dark comedy, it had moments where it flirted with being downright disturbing, like the Ross family arc. Susan Ross (Heidi Swedberg) was George Costanza’s longtime girlfriend and, briefly, fiancée before she died from licking toxic wedding envelopes George chose to save money. Played by Twin Peaks alumni Warren Frost and Grace Zabriskie, Mr. and Mrs. Ross never liked George and made no secret that they thought he was terrible for their daughter.

By the finale of Seinfeld, Mr. Ross is fully convinced that George deliberately murdered his daughter. We even see him buying a gun, presumably in case George and his friends are acquitted for their myriad crimes and social wrongs. While Frost’s turn as Doc Hayward in Twin Peaks overshadowed his five episodes of Seinfeld, fans of the show continue to remember details about him fondly—especially a passing reference to his affair with author John Cheever, which made him one of the first bisexual television characters in history. Frost passed away in February 2017 after a long illness. He was 91 years old and made his final appearance in Twin Peaks’ third season.

Daniel von Bargen (Mr. Kruger)

Most of George Costanza’s bosses expected far more from him than he was ever able to provide, but not Mr. Kruger, George’s beleaguered boss at Kruger Industrial Smoothing. He mirrors George’s lackadaisical manner in so many ways. Played by character actor Daniel von Bargen, Mr. Kruger has a few iconic plotlines even though he’s only in four Seinfeld episodes.

Kruger’s first major story involves a trip to the beach with his family and a resulting photograph that George mucks up completely. His most memorable appearance arguably comes when George tries to convince him that his fictional charity, The Human Fund, is real. George’s attempt at persuasion ends with Kruger joining him for Festivus "celebrations" at the Costanza home. With his deadpan expression and comedic timing, von Bargen’s Kruger absolutely steals the scene—a remarkable feat among so many other talented actors.

Tragically, von Bargen passed away in March 2015 at the young age of 64 after a long battle with diabetes complications, mental illness, and a tragic suicide attempt.

Reni Santoni (Poppie)

Most of Jerry’s many failed dates and relationships had nothing to do with the woman in question. We first meet Poppie, the owner of a well-known Italian pizzeria, when Jerry starts dating his daughter, Audrey (Suzanne Snyder). The date takes a disastrous turn when Jerry sees that Poppie doesn’t wash his hands after using the toilet, causing Jerry to refuse to eat the hand-tossed pizza Poppie made especially for them and insulting both father and daughter in the process.

In just four episodes, Poppie manages to cause quite a lot of damage, including with a medical condition that causes him to unknowingly urinate first on Jerry’s new couch, then George’s. Poppie’s enmity with the group extends to Elaine; their conflicting views on abortion land Poppie in the hospital due to stress. The actor who played Poppie, Reni Santoni, was best known for his role as Clint Eastwood‘s partner in Dirty Harry, and passed away at 81 in August 2020 after a long illness.

Billye Ree Wallace (Nana)

You’d think after so many years on air and in reruns, Seinfeld would bring us a little bit closer to understanding how Jerry’s brain works, but as we see with the Nana subplot, his behavior remains a mystery. Played by Billye Ree Wallace for three episodes, Jerry’s Nana is minding her own business when Jerry suddenly decides to cash all the $10 checks she’d been sending him for his birthday for many, many years. Because Nana no longer has that particular account anymore, the checks bounce, and she gets dressed up in her finest to go down to the bank to get it sorted out. Unfortunately, Nana discovers the bank isn’t there anymore, the neighborhood is scarily run-down, and she’s even threatened by a hoodlum. Oy vey.

Like many of her Seinfeld co-stars, Wallace was a well-known character actress who appeared in shows like Mad About You as well as films like Albert Brooks’ Mother. In March 1999, Wallace passed away from respiratory failure and emphysema at the age of 73.

Frances Bay (Mabel Choate)

If there’s one thing we know for certain about Jerry Seinfeld, it’s that he’s selfish and opportunistic. There’s little he won’t do to get what he wants, no matter how petty it is. Enter Mabel Choate, an elderly woman who simply wants a nice marble rye. Jerry, being Jerry, wants the loaf for himself to replace the one that George stole from Susan’s parents, so he attacks Mabel and steals her bread. It’s dark out, so Mabel doesn’t recognize her assailant until another inopportune moment: when Morty Seinfeld is being impeached. Mabel Choate also testifies against Jerry at the trial in the series finale, noting that he never expressed remorse for stealing from her, a little old lady.

For three episodes, character actress Frances Bay plays Mabel, bringing scathing wit and impeccable comedic timing to this very physical role. Bay passed away at 92 years old in September 2011 after an accident left her with an amputated leg and a series of unfortunate health complications followed.

Elmarie Wendel (Helena)

Every single character in Seinfeld is a certified drama queen whose unnecessary shenanigans take the story to Bizarro World and back, but the most absurd of them all might be Cosmo Kramer. His wacky entrances into Seinfeld’s apartment have an entire category of their own in Seinfeld’s behind-the-scenes commentary, Notes About Nothing. In season four, Kramer gets annoyed with his gang of friends in New York and decides he wants to go to Los Angeles to be an actor. During his unsuccessful quest to get his grizzled mug on television or in a movie, he meets Helena, a former actress who haunts the hallways of his new apartment building.

Played by Elmarie Wendel, Helena is a send-up of Hollywood queen Norma Desmond in Sunset Boulevard, stealing the show as she descends the stairs with her sometimes inappropriate commentary. Wendel might have been better known for her turn as Mrs. Dubcek on Third Rock From the Sun, but Seinfeld fans will still be saddened to hear of her passing in July 2018 of undisclosed causes. She was 89.

Lloyd Bridges, Gene Dynarski, and Earl Schuman (the Mandelbaums)

There are three Izzy Mandelbaums in Seinfeld: Izzy Sr., Izzy, and Izzy Jr. Comically, all three generations of this family appear to be roughly the same wizened age. Izzy is a resident of Del Boca Vista, and all three men work at their family’s restaurant, The Magic Pan.

Izzy the second and third, played by Lloyd Bridges and Gene Dynarski, respectively, are two of the most competitive people to grace Seinfeld‘s soundstage. Izzy first gets our attention when, irritated by Jerry, he challenges him to feats of physical prowess that land Izzy in the hospital. While visiting Izzy’s sickbed, Jerry runs into Izzy Jr., who throws his back out trying to goad Jerry into lifting a hospital television that’s bolted to a table. Finally, Izzy Mandelbaum Sr. appears and also tries to best Jerry. By the end of this absurdity, all three Izzys are incapacitated, but still trying to provoke fights with anyone who speaks to them.

Sadly, all three Mandelbaum actors have passed away. Hollywood icon (and father of Jeff Bridges) Lloyd Bridges died in March 1998 at 85 after several illnesses, Gene Dynarski passed in April 2020 after a series of heart issues, and Mandelbaum patriarch Earl Schuman died of undisclosed causes at 100 years old in March 2016.

Sam Lloyd (Ricky)

In Elaine’s extensive catalog of men who become obsessed with her, Ricky is one of the creepiest. Played by Sam Lloyd (nephew of Christopher Lloyd), Ricky becomes fixated on Elaine over two Seinfeld episodes. When we first meet Ricky, he’s sitting next to Elaine on the subway and offers her a highlighter to help with the TV Guide she’s reading. His intensity freaks Elaine out. In her rush to get away from him, Elaine forgets her magazine on the subway seat—only, it’s not her magazine, but Frank Costanza’s. He’s none too pleased when Ricky stalks Elaine to the Costanza house having made a bizarre bouquet out of Frank’s TV Guide. The next time we meet Ricky, his obsession has veered into mild psychopathy; he designs mannequins that look just like Elaine, distributing them all over New York City and keeping one in his apartment.

Unfortunately, Scrubs actor Sam Lloyd was only 55 when he was diagnosed with a brain tumor and lung cancer. He succumbed to his illnesses in May 2020 at the age of 56.