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

Helberg has appeared on the sketch comedy series MADtv and is also known for his role as Moist in Joss Whedon's web miniseries Dr. Horrible's Sing-Along Blog (2008). He has further performed in films such as Old School (2003), Good Night, and Good Luck (2005), Walk Hard: The Dewey Cox Story (2007) and A Serious Man (2009).