William Katt (gebore 16 Februarie 1951) is 'n Amerikaanse akteur, regisseur, en skrywer. Hy is bekend vir sy rolle in die rolprente Carrie (1976), House (1985), en The Man from Earth (2007), en in die televisiereeks The Greatest American Hero (1981).
- 1976: Carrie
- 1977: First Love
- 1978: Big Wednesday
- 1979: Butch and Sundance: The Early Days
- 1985: House
- 1985: Baby: Secret of the Lost Legend
- 1988: White Ghost
- 1989: Wedding Band
- 1990: Naked Obsession
- 1991: Last Call
- 1992: Double X: The Name of the Game
- 1993: Distant Cousins
- 1994: The Paper Boy
- 1995: Piranha
- 1996: Daddy's Girl
- 1997: u'Bejani
- 1998: Hyacinth
- 2000: Clean and Narrow
- 2002: Determination of Death
- 2002: Treading Water
- 2002: Snake Island
- 2003: Descendant
- 2005: River's End
- 2007: The Man from Earth
- 2008: Big Game
- 2009: Deadland
- 2010: Earthling
- 2011: The Encore of Tony Duran
- 2012: The Jonas Project
- 2013: .357
- 2014: The Unwanted
- 2015: Subterranea
- 2015: Crusty Demons 18: Twenty Years of Fear
- 2017: The Man from Earth: Holocene
- 1981: The Greatest American Hero
- 1989: Top of the Hill
- 1991: Good Sports
- 1981: Pippin: His Life and Times
- 1982: The Rainmaker
- 1985: Perry Mason Returns
- 1986: Perry Mason: The Case of the Notorious Nun
- 1986: Perry Mason: The Case of the Shooting Star
- 1987: Perry Mason: The Case of the Lost Love
- 1987: Perry Mason: The Case of the Murdered Madam
- 1987: Perry Mason: The Case of the Scandalous Scoundrel
- 1987: Perry Mason: The Case of the Sinister Spirit
- 1988: Perry Mason: The Case of the Avenging Ace
- 1988: Perry Mason: The Case of the Lady in the Lake
- 1989: Swimsuit
- 1991: Ghost Writer
- 1995: American Cop
- 1995: Problem Child 3: Junior in Love
- 1996: Devil's Food
- 1996: Rattled
- 1996: Romantic Undertaking
- 1998: Catch Me If You Can
- 2002: Gentle Ben
- 2002: Surf Now Apocalypse Later
- 2011: Moon
- Rick's Parking
- 1986: The Making of 'House'
- 1992: House IV
- 1994: Stranger by Night
- 2001: Acting 'Carrie'
- 2007: AVH: Alien vs. Hunter
- 2010: Keeping It Real: The Visual and Special Effects of Mirrors 2
- 2016: More Acting 'Carrie'
- 2017: Home Deadly Home: The Making of House IV
- 2018: George of the Jungle with William Katt