He died in hospital after being treated in an intensive care unit after suffering a brain aneurysm two weeks ago, according to his manager Charles Lago.
Sizemore, 61, was a prominent actor in the 1990s and early 2000s, appearing in films such as “Heat,” “Saving Private Ryan” and “Black Hawk Down.”
In 2003, he was convicted of assaulting his then-girlfriend, and Sizemore has since had long-term substance abuse problems.