Of Unknown Origin

Of Unknown Origin
Of Unknown Origin
	Theatrical release poster
Directed by	George P. Cosmatos
Screenplay by	Brian Taggert
Based on	The Visitor; by Chauncey G. Parker III
Produced by	Claude Héroux
Starring	Peter Weller; Jennifer Dale; Lawrence Dane; Kenneth Welsh; Louis Del Grande; Shannon Tweed;
Cinematography	René Verzier
Edited by	Roberto Silvi; Hubert de La Bouillerie
Music by	Kenneth Wannberg
Production; companies	Les Productions Mutuelles; Famous Players; Canadian Film Development Corporation;
Distributed by	Mutual Productions (Canada); Warner Bros. (U.S.)
Release dates	September 30, 1983 (Fresno, California); November 23, 1983 (U.S.); November 25, 1983 (Canada);
Running time	89 minutes
Countries	Canada; United States
Language	English
Budget	CAD$4 million
Box office	$1.1 million (U.S.)

Of Unknown Origin is a 1983 psychological horror film directed by George P. Cosmatos in his North American film debut, and starring Peter Weller, Jennifer Dale, Lawrence Dane, Maury Chaykin, Kenneth Welsh, Louis Del Grande and Shannon Tweed in her film debut. Based on the 1979 novel The Visitor by Chauncey G. Parker III, it focuses on a mild-mannered Manhattan banker who becomes increasingly obsessive and destructive in his attempts to kill a rat loose in his renovated brownstone. The film's title refers to the misconception (repeated in the film) that rats have no known origin.

A co-production between Canada and the United States, the film was primarily shot in Montreal, with some additional shooting taking place in New York City. The film was released theatrically on November 24, 1983 by Warner Bros. It received generally positive reviews from critics, with much praise for Weller's leading performance. Writer Stephen King has named it one of his favorite horror films.