The actor passed away Friday in an L.A.-area hospital after his family made the difficult decision to remove him from life support. The actor had been receiving treatment after suffering a brain aneurysm at his home on February 18, which caused him to collapse and lose consciousness.

Tom's rep, Charles Lago, tells TMZ, "It is with great sadness and sorrow I have to announce that actor Thomas Edward Sizemore (“Tom Sizemore”) aged 61 passed away peacefully in his sleep today at St Joseph’s Hospital Burbank. His Brother Paul and twin boys Jayden and Jagger (17) were at his side."

TMZ broke the story ... Tom was rushed to the ER around 2 AM, and was listed in critical condition while doctors worked on him in the ICU. He never regained consciousness.

Tom's manager, Charles Lago, told us his condition still wasn't good a week after the incident ... remaining in a coma in the ICU with no signs of improvement. We were told the medical staff at his location recommended an end-of-life plan, laying out options for the family.

Lago also said Tom's aneurysm was the result of a stroke he suffered, causing him to collapse.

Sizemore's legacy is certainly mired in controversy -- especially in his later years -- but for a time, he was a sure thing in Hollywood, especially as he started to blow up following a string of career-changing roles throughout the '90s, like the one he landed in Spielberg's World War II epic.

In 'SPR,' TS played Sergeant Horvath opposite Tom Hanks and other big actors as they sought out Matt Damon's character to relieve him of duty. Sizemore's performance was a standout one, and it actually earned him a couple award nominations.

Even before 'Ryan' ... Sizemore had already racked up several notable roles in flicks like "Where Sleeping Dogs Lie," "Passenger 57," "True Romance," "Natural Born Killers," "Devil in a Blue Dress," "Heat," "Enemy of the State" and lots of others. By this point, he'd carved out a nice little archetype for himself, often playing a tough guy and/or a hardened criminal.

The 2000s and the decades thereafter weren't nearly as memorable for Sizemore, but he continued to act in a lot of films -- the most noteworthy of which include ... "Pearl Harbor," 'Black Hawk,' "Dreamcatcher," "Red Planet" and "Paparazzi."

The late 2000s and 2010s saw Tom padding his resume with a lot of B-movie-level flicks/shows. All in all, he had 230 acting credits to his name -- but the appeal he held some 30 years ago had largely faded. Of course, Sizemore also battled addiction throughout his career.

He had been arrested on a handful of occasions ... a couple of times for domestic violence, and frequently for substance abuse-related offenses. Sizemore had been in and out of rehab for his addictions.

He's survived by 2 sons. Sizemore was 61.