Movies You Haven't Seen But Should: Targets

Wiki:

Targets (1968) is a film written, produced and directed by Peter Bogdanovich.

The story concerns an insurance agent and Vietnam veteran, played by Tim O'Kelly, who murders his wife and mother and then goes on a shooting rampage from atop a Los Angeles oil refinery. When police start tracking him down, he flees to and resumes his shootings at a drive-in theater where an aging horror film actor is making a final promotional appearance.

The character and actions of the killer are patterned after Charles Whitman, the University of Texas sniper. The character of actor Byron Orlok, named after Max Schreck's vampire Count Orlok in 1922's Nosferatu, is patterned after Boris Karloff himself, who in fact plays the part in his last appearance in a major American film (although Bogdanovich states that, unlike Orlok, Karloff was not embittered with the movie business and did not wish to retire).

In the film's finale, which takes place at a San Fernando Valley drive-in theater, Karloff — the old-fashioned, traditional screen monster who always obeyed the rules — confronts the new, nihilistic late-1960s monster in the shape of a clean-cut, unassuming multiple murderer.