C
- C-3PO, explains to R2D2 that the thing he is in love with is a fire hydrant. "It is better to have loved a fire hydrant than to never have loved at all" in episode 1396. This is their second appearance, the first one is episode 1364.
- Sid Caesar
- Cab Calloway
- John Candy, appeared in the Put Down the Duckie special, 1988.
- Steve Carell
- José Carreras
- Jim Carrey
- Roger Carrier I
- Aaron Carter, Teaching Elmo about siblings
- Nick Carter, Teaching Elmo about siblings
- Vince Carter
- Nancy Cartwright (as Bart Simpson)
- Johnny Cash
- Dan Castellaneta (as Homer Simpson)
- Phoebe Cates
- Kim Cattrall, defines the word 'fabulous' for Abby Cadaby in episode 4162
- Cedric The Entertainer - demonstrates the word 'canteen' with Abby
- Carol Channing
- Stockard Channing
- Ray Charles sings alphabet song
- Cher
- Margaret Cho
- Hillary Clinton
- Rosemary Clooney
- Chuck Close
- Glenn Close
- Bill Cobbs
- Stephen Colbert, as the letter Z in Sesame Street's All Star Alphabet
- Laveranues Coles, one segment: Coles, a New York Jets player, appears during in season 38 (2007), along with other Jets, Elmo, and Elmo's goldfish Dorothy.
- Judy Collins
- Shawn Colvin sings "I Don't Want to Live on the Moon" with Ernie.
- Harry Connick Jr.
- Tim Conway
- Anderson Cooper, appeared on GNN to discuss the letter G
- Angel Corella
- Bill Cosby
- Elvis Costello
- Katie Couric
- Sheryl Crow
- Celia Cruz
- Billy Crystal
- Jane Curtin
- Jamie Lee Curtis
Read more about this topic: List Of Guest Stars On Sesame Street