Simon Maxwell Helberg (born December 9, 1980) is an American actor, comedian, and musician. He is known for playing Howard Wolowitz in the CBS sitcom The Big Bang Theory (2007–2019), for which he won the Critics' Choice Television Award for Best Supporting Actor in a Comedy Series, and as Cosmé McMoon in the film Florence Foster Jenkins (2016), for which he was nominated for the Golden Globe Award for Best Supporting Actor – Motion Picture.

He has appeared on the sketch comedy series MADtv, and has appeared in films such as Old School (2003), Good Night, and Good Luck (2005), Walk Hard: The Dewey Cox Story (2007), A Serious Man (2009), and Annette (2021).

He wrote, directed (along with his wife Jocelyn Towne), and starred in the film We'll Never Have Paris (2014), which is based on he and his wife's relationship.