William Mills Irwin (born April 11, 1950) is an American actor, choreographer, clown, and comedian. He began as a vaudeville-style stage performer and has been noted for his contribution to the renaissance of the American circus during the 1970s. He has made several appearances on film and television. He won a for his role in Who's Afraid of Virginia Woolf? He also worked as a choreographer on Broadway. He was nominated for the Tony Award for Best Choreography in 1989 for Largely New York. He is also known as Mr. Noodle on the Sesame Street segment Elmo's World, and he appeared in the Sesame Street film short Does Air Move Things? He has regularly appeared as Dr. Peter Lindstrom on Law & Order: Special Victims Unit and had a recurring role as "The Dick & Jane Killer" on CSI: Crime Scene Investigation. From 2017 to 2019, he appeared as Cary Loudermilk on the FX television series Legion.