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.

Somehow, Maria Menounos got a smile out of Oscar the Grouch when the hostess with the mostest shared a scene with him about senses.

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.

It doesn’t get any more legendary than the late Tony Bennett and Elmo, does it?

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.

There are a handful of careers that amaze children, and astronaut is one of them. So, to see Buzz Aldrin on Sesame Street teaching the children about space was an unforgettable moment.

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.

There is nothing more beautiful than singer-songwriter James Blunt and Telly Monster singing about triangles. 

Liev Schreiber  and Naomi Watts appeared together on the show's 42nd season to help teach young viewers, like their two children, what "exchange" meant.