Which actor did not have a single bad film?

John Cazale.

Only appeared in 5 films but all five were nominated for Best Picture at the Oscars:

The Godfather (1972)
The Godfather Part II (1974)
The Conversation (1974)
Dog Day Afternoon (1975)
The Deer Hunter (1978)

Died of lung cancer in March 1978, aged 42 ☹️