Bella Lugosi

Reason for leaving cinema:
Lugosi died of a heart attack supposedly holding the script for The Final Curtain. He was buried in a Dracula costume, seriously.

Final Film: Plan 9 from Outer Space
Lugosi's final role, hilariously reconstructed in Tim Burton's Ed Wood by Martin Landau, was the infamous Plan 9 from Outer Space, often considered to be the worst film ever made. After his untimely death, the remainder of his scenes were filled by a body double, his wife's chiropractor, who was much thinner than the Prince of Darkness.