Since 1969, the series "Sesame Street" has offered young viewers a friendly, imaginative place where important lessons – both educational and social – are addressed through a diverse cast of humans and puppets using irreverent humor and relatable situations to impart their message. The series, produced by Sesame Workshop (formerly known as the Children’s Television Workshop), has created some of the most beloved figures in children’s programming, including Big Bird, Elmo, Oscar the Grouch, and Grover – all Muppet creations of puppeteer Jim Henson and operated originally by him and future "Muppet Show" vets Frank Oz and Jerry Nelson. The show also brought us the magic of Caroll Spinney, who operated both Big Bird and Oscar for nearly 50 years.

"Sesame Street" has also featured a host of actors who have gone on to become well-loved figures for young viewers, many of whom, like Bob McGrath (who played the kindly Bob) and Roscoe Orman (the fatherly Gordon), remained with the series for decades. Like many long-running shows, "Sesame Street" has undergone numerous cast and creative personnel changes over the years, and now airs on PBS and HBO Max.

Below is a list of some beloved "Sesame Street" actors who may have helped shape your childhood — and who you might not realize have since passed away.

Jim Henson – master of muppets

Though "Sesame Street" has always featured vibrant and multitalented human performers, award-winning writing and memorable animation and live-action segments, its most enduring element is inarguably its cast of Muppets. Big Bird, Elmo, Cookie Monster, and other such creations have transcended the simple, one-dimensional puppets that populated children’s programming before the show came on — sorry Howdy Doody, you just can’t hold a candle to Cookie Monster. The engine that fueled the Muppets from day one — and in the case of Kermit the Frog, Ernie, and others, actually operated them — was legendary puppeteer, writer, and director Jim Henson.

Henson would parlay the success of the Muppets on "Sesame Street" and their own syndicated series "The Muppet Show" into numerous feature film ("Labyrinth" and "Dark Crystal," among them) and television projects (like "Fraggle Rock" and "Emmet Otter’s Jug-Band Christmas"). But his energy and creativity, which at times seemed boundless (and earned Henson multiple Emmys, Grammys, and other awards) was cut short on May 15, 1990, when Henson was hospitalized with breathing difficulties in New York City. The cause of the sudden illness — a bacterial infection that spread to his internal organs — resulted in Henson’s death at the age of 53 the following day.

Henson is still considered one of the true geniuses of our time, as exemplified in a classic Apple ad. Disney and the Jim Henson Company are currently developing a film about Henson’s life.

Caroll Spinney: He was Big Bird (and Oscar)

For nearly a half-century, whole-body puppeteer Caroll Spinney played Big Bird, the eternally six-year-old and perpetually curious heart and soul of "Sesame Street," as well as the embodiment of the show’s mission to connect children with education through entertaining stories and characters. Playing the eight-foot-two-inch bird was a challenge – Spinney operated Big Bird’s head with one upraised hand and one wing with the opposite arm while also watching the scene (and reading his lines) from a monitor and script, respectively, inside the costume.

When not operating Big Bird, Spinney also voiced and operated another iconic character, Oscar the Grouch. The character’s prickly attitude — a counterpoint to the "sunny days" perspective of the rest of the cast — made him an immediate pop culture icon for dyspeptic types, and led to appearances outside the "Sesame Street" universe, including "Portlandia," "Scrubs," and "Night at the Museum."

Spinney operated both Big Bird and Oscar until 2015, when the physical demands of both characters forced him to step down as puppeteer. He continued to record the voices for his beloved roles until retiring from the series in 2018. Spinney, who won four Daytime Emmys and a Lifetime Achievement Award from the National Academy of Television Arts and Science (and was the subject of a 2015 documentary, "I am Big Bird") died at his home in Woodstock, Connecticut on December 8, 2019, at the age of 85.