Sesame Street's original star Big Bird has led the show since its first episode in 1969. The 8-foot Muppet often doesn't understand what's going on but sets the tone for the show by never hesitating to find out.
2013. Sesame Workshop. All rights reserved
"Sesame Street's" Muppet characters were originally intended to be support for the human cast, but test audiences responded so warmly to Bert and Ernie's sketches that the producers put Muppets in starring roles. The comic duo have been two of the show's most popular characters ever since.
2013. Sesame Workshop. All rights reserved
Sonia Manzano played shop owner Maria for nearly 45 years before retiring in July. She also worked as a writer for the show.
Richard Termine/Sesame Street
Alan Muraoka is the owner of Hooper's Store. He also works as a performer on Broadway.
Richard Termine/Sesame Street
Alison Bartlett O'Reilly took the role of Gina, an assistant at Hooper's Store and babysitter for Elmo and Zoe. She joined the ensemble in 1987.
Richard Termine/Sesame Street
Bob McGrath was one of the first four human cast members on Sesame Street. He is known for his music and singalongs, although Bob can also tell a good story or two.
Richard Termine/Sesame Street
Christopher Knowings helps out at Hooper's Store. He was cast in 2006.
Richard Termine/Sesame Street
Emilio Delgado, who plays Luis, was the first human cast member. When something needs to be fixed, he is the man to call.
Richard Termine/Sesame Street
Ismael Cruz Cordova is a new addition as Armando. He's best known for his role in the CBS drama "The Good Wife."
Richard Termine/Sesame Street
Loretta Long has played Susan since the show's beginning. When Big Bird needed comforting, Susan was there to help, and she is known for her maternal instincts.
Richard Termine/Sesame Street
Nitya Vidyasagar joined "Sesame Street" as Leela. The recent addition has a background in theater performance.
Richard Termine/Sesame Street
Roscoe Orman has played Gordon, husband to Susan, since Sesame Street began. Orman's real-life son Miles joined the cast in season 17 as Gordon's son, solidifying Orman's role as a kind and caring father.
Richard Termine/Sesame Street
The Muppet Show made him a star, but Kermit the Frog had begun winning younger fans on "Sesame Street," explaining to kids that "It's Not Easy Bein' Green" for the first time in 1970.
Courtesy Disney Enterprises, Inc
Fifteen years passed between the premiere of "Sesame Street" and Elmo getting his big break in 1984. But since then, the furry red monster with the high-pitched voice has gone on to become arguably the show's most popular Muppet.
2013. Sesame Workshop. All rights reserved
"Om nom nom nom" -- Cookie Monster's voracious appetite for his favorite chocolate chip treats have endeared him to viewers since "Sesame Street's" first season. He's even managed to fit in teaching some important lessons: Thanks to him, generations of kids have grown up knowing that "C" is for cookie.
2013. Sesame Workshop. All rights reserved
A bad-tempered green monster who loves "anything dirty or dingy or dusty" and lives in a trash can: perhaps not an obvious choice for a children's TV hero. Yet Oscar the Grouch, whose ambition is to be as miserable as possible, has failed to ruin viewers moods, bringing humor and fun to the Street.
2013. Sesame Workshop. All rights reserved
Zoe broke into "Sesame Street's" largely male Muppet cast in 1994, becoming the show's stand-out female character. As she appears to be about the same age as Elmo, the two often spend time together. They are understood to be best friends.
2013. Sesame Workshop. All rights reserved
Nothing can interrupt the Count when he's counting. Whether counting from one to 10 or up to a billion (as he did in 2013 to celebrate "Sesame Street's" 1 billion YouTube views), the Count is happiest with numbers. He can now count over 40 years of appearances on "Sesame Street" since his debut in 1972.
2013. Sesame Workshop. All rights reserved
Is Grover the coolest Muppet on "Sesame Street"? He certainly thinks he is and describes himself as a "cute, furry little monster." Grover is one of the favorite creations of "Sesame Street" puppeteer Frank Oz, who said his generous personality and distinctive way of pronouncing each word "came about organically" when he brought the Muppet to the Street in 1970.
2013. Sesame Workshop. All rights reserved
For many years, the adults on "Sesame Street" didn't believe that Mr. Snuffleupagus was real. The gigantic Muppet had an uncanny way of disappearing just before adult characters arrived, and many assumed he was Big Bird's imaginary friend. The very real Muppet is one of the Street's most cultured residents, revealing a love of ballet, opera and art since his first appearance in 1971.