Don Siegel was the director of
Clint Eastwood's breakthrough film
Dirty Harry. He formed a close relationship with Eastwood,
mentoring him as a director as well. Directing Eastwood in five films altogether before his death of
cancer in
1991, Siegel earned a most public vote of thanks from his
protégé in the closing credits of Eastwood's
Academy Award-winning film
Unforgiven. At the finish, a dedication reads simply "For Sergio and Don." Sergio is
Sergio Leone, who directed Clint in his early westerns such as
A Fistful of Dollars.
Sources: IMDB and Clint Eastwood: Out of the Shadows