Robin Williams often joked on stage about his love of cocaine, once cracking, "What a wonderful drug, anything that makes you paranoid and impotent, give me more of that."  But his battle with drug addiction and depression was apparently a serious one, as he died Monday of an apparent suicide. 

When it comes to comedians battling serious conditions such as drugs and depression, Williams is not alone.

Comedians often have high levels of psychotic characteristics related to manic depression, according to a 2014 study by The British Journal of Psychology.

Here's a list of five other comedians who committed suicide:

1.       Chris Farley: A comedian and actor who appeared on "Saturday Night Live" between 1990 and 1995. He overdosed on drugs at age 33.

2.       John Belushi: A comedian, actor and musician who was best known as an original "Saturday Night Live" cast member. He died from a cocaine and heroin overdose at age 33.

3.       Freddy Prinze: A comedian and actor who was best known for starring in the 1970s sitcom "Chico and the Man." He died at age 22 after shooting himself.

4.       Ray Combs: A comedian and actor who was best known for being the "Family Feud" game show host from 1998-1994. He hung himself in the psychiatric ward of Glendale Adventist Medical Center in Glendale, Calif., at age 40.

5.       Tony Hancock: A comedian and actor who was best known from his BBC series "Hancock's Half Hour," first on radio from 1954, then on television from 1956. He died after an alcohol overdose at age 44.