A comprehensive list.

Missing from Letterboxd:
The Eccentric Dancer (1900)
First Man to the Moon (1921)
Koko Gets Egg-Cited (1926)
Koko Makes 'Em Laugh (1927)
Noise Annoys Ko-Ko (1929)
Pink Lemonade (short, 1936) feat. Toto the Clown and The Cabin Kids
Here Comes the Circus (1946) (short film, USA)
Kloun (1977) animated short, 1 min., (Soviet Union)
Clowning Around 2 (1992, Australia)
Mariah Carey: Fantasy (1995, music video)
A Clown in Babylon (1999)
The Secret Life of Clowns (2004) (short film, USA)
Music Video for Arctic Monkeys' "Fluorescent Adolescent" (2007), directed by Richard Ayoade
A Clown Carol: The Marley Murder Mystery (2007) (short film, USA)
Clowning Around (2010) (comedy short)
The Pogo Film Project (2012)
No Clowning Around (2012) (horror short)
Music Video for Alice In Chains' "The Devil Put Dinosaurs Here" (2013)
Clowning Around (2013) (comedy short)
Clowne (2014) (comedy short, Norway)
Death: A Love Story (2015)
The Evil One (2017)
C is for Clown (horror short, 2019)

A selection of television series featuring clowns:
Psychoville (2009–2011)
Sending Out the Clowns (2011- )
Season 4 of "American Horror Story", "Freak Show" (2014-15)

Also see:
www.youtube.com/watch?v=O2vBJt1iG60
www.youtube.com/watch?v=QbVaJ-pUOXQ
www.youtube.com/watch?v=IDJDtosYKow
www.youtube.com/watch?v=ukWR73gJ2qM
www.youtube.com/watch?v=U-h4f6BKW_8