He provided the role of The Stranger to actor
Tony Anthony
and played the villain in The Stranger's first movie
Un dollar entre les dents (1967) as a favor for Anthony. The part became Anthony's most famous role besides his
Blindman, le justicier aveugle (1971) and he repeated it three times. Several months before Frank Wolff's death, according to Anthony
himself, Frank Wolff asked him for a similar favor, wanting the role in
Blindman, le justicier aveugle (1971), which was finally taken by
Ringo Starr. It was kind of deal between them, Anthony would provide him role, because Wolff had done him a favor earlier.
But the producers wanted Ringo Starr for the role - Wolff was dropped and had a falling out with Anthony. About one year later Frank Wolff killed himself. There have always been rumors, one reason for the suicide was, he saw his career at an end/thought he couldn't get the roles he wanted anymore.