20 celebrities who’ve appeared on ‘Sesame Street’

Bruno Mars not only entertained but encouraged singing "Don't Give Up."

Jennifer Garner brought a pretty big word to the table when she explained "galoshes" to the always-interested Abby Cadabby.

Lin-Manuel Miranda brought that Hamilton charm to pizazz to Sesame Street to rap about habitats alongside the one and only Big Bird.

The actress once appeared on the educational program to introduce Elmo and the young viewers to the word “ingredient.”

If there was ever a celebrity made for Sesame Street, it was Robin Williams and his childlike wonder and good-natured spirit.

Katy Perry didn't just come to educate — she also came to perform! She sang a revised version of her hit single, "Hot N Cold," featuring Elmo.

It couldn't have been easy, but Sir Ian McKellen was up for the task when it came to teaching Cookie Monster about resisting.

Grammy winner Alicia Keys didn't hesitate when asked to sing a song all about dancing to the tune of her debut single, "Fallin.’"

Mark Ruffalo is best known for being the Incredible Hulk in the Marvel Universe, but he showed a lot of heart when he came through with a lesson on empathy.

Nicole Kidman and Oscar the Grouch educated about what stubborn means, but perhaps one day she'll return and explain the magic of movie theaters.

Adam Sandler has had a lot of entertaining costars, so one has to wonder where he’d rank Cookie Monster. Probably pretty high on the list. It’s Cookie Monster!

Who wouldn't have a smile as vibrant as Guardians of the Galaxy actress Zoe Saldaña while hanging out with Elmo?

Frozen's Josh Gad has said his favorite memory of Sesame Street revolves around watching it with his daughter, so she must've been extra stoked to see her dad on the show!

Modern Family star Julie Bowen and Elmo likely started a bird-watching club after she taught him about the ins and outs of binoculars.

Nick Jonas flew solo for a minute and landed onstage in Sesame Street with a few new band members.

When it comes to Oscar-winner Lupita Nyong'o and Elmo, the word of the day is iconic.

Tony Soprano himself, the late James Gandolfini showcased a lot of levels on the hit HBO series that helped usher in a new era of anti-heroes, but did you know that he showcased even more when he stopped by Sesame Street to talk about what it is like to feel scared?

Emma Stone has a multitude of talents, including balancing, which is what she demonstrated when she hit Sesame Street.

Johnny Galecki once took time away from his hit CBS series, The Big Bang Theory, to hit up Sesame Street's 42nd season, and to work with the always-exciting Abby Cadabby. They both look super excited to be with one another.

Amy Poehler is such a pro, that it probably wasn’t a challenge for her when she stopped by Sesame Street to demonstrate and teach Elmo the word, “challenge.”