11. Jason Mraz
"April in Quahog," April 11, 2010
Jason Mraz is a Grammy award-winning singer/songwriter who rose to fame with the single "I'm Yours." He played Some Guy with a Hat, who Peter thinks is Jason Mraz.
12. Sean Bean
"No Country Club for Old Men," May 19, 2013
Sean Bean is a veteran actor, starring in the Lord of the Rings movies as Boromir, as well as Ned Stark in Game of Thrones. In this episode, the British actor voiced one of Peter Griffin's ancestors in a portrait.
13. Jon Cryer
"A Hero Sits Next Door," May 2, 1999
Jon Cryer is famous for being one whole of Two and a Half Men. He voiced Kevin Swanson, Joe's son, in only this episode. Kevin is voiced other times by Seth MacFarlane until the tenth season, when Scott Grimes (American Dad) takes over.
14. Elizabeth Banks
"Into Fat Air," September 30, 2012
Elizabeth Banks is a talented actress, deftly handling comedy, like in 30 Rock, and drama, like in The Hunger Games movies. (Although she still manages to provide comic relief amid the tragedy.) She also voiced Wyldstyle in The LEGO Movie. In this episode, she voiced Pam Fishman, the wife of Ross Fishman. Peter challenges Ross to race to the top of Mount Everest.
15. Dakota Fanning
"To Love and Die in Dixie," November 15, 2001
Dakota Fanning became famous at a very early age for her amazing work in I Am Sam, opposite Sean Penn. That year she also voiced "Little Girl" on Family Guy, who tells Meg her daughter would love her. Since then Dakota Fanning has starred in Taken, War of the Worlds and the Twilight series of movies.
16. Ryan Reynolds
"Jesus, Mary and Joseph," December 23, 2012
Ryan Reynolds appeared in two episodes as the Overweight Guy, including this one when he was the first son of God. Ryan Reynolds has starred in romantic comedies, like The Proposal, and action films, like Green Lantern. He was spotted as Deadpool in X-Men Origins: Wolverine and is expected to reprise that role in an upcoming Deadpool movie.
17. Hugh Laurie
"One if by Clam, Two if by Sea," August 1, 2001
Hugh Laurie is most famous for playing Dr. Gregory House in House M.D. In this episode he voiced a bar patron who explains to Peter how cricket is played.
18. Will Ferrell
"Fifteen Minutes of Shame," April 25, 2000
Will Ferrell is known for the many movie comedies he's starred in, including Anchorman: The Legend of Ron Burgundy, The Campaign, The Other Guys and Old School. In this Family Guy episode, he played two roles: Fat Greek Guy and Miles "Chatterbox" Musket, the found of Quahog.
19. Ricky Gervais
"Be Careful What You Fish For," February 19, 2012
Ricky Gervais played Billy Finn, the talking dolphin who shows up on Peter's doorstep. Ricky Gervais is a world-famous comedian, writer and actor. His most famous work is The Office. He also starred in Extras and The Ricky Gervais Show on HBO.
20. Cary Elwes
"Secondhand Spoke," March 30, 2014
Forever known as Westley in The Princess Bride, Cary Elwes voiced the role of Dr. Watson (as in Sherlock Holmes) in a cutaway scene when Chris tells Stewie how well they work together.