He earned praise for his work in films like “Saving Private Ryan” and “Black Hawk Down.” He also served prison time for drug possession and domestic abuse.Tom Sizemore, a tough-guy actor whose career, which included roles in major films like “Saving Private Ryan” and “Black Hawk Down,” was overshadowed at times by his problems with substance abuse and the law, died on Friday in Burbank, Calif. He was 61.The death was announced by his manager, Charles Lago. The cause was not immediately known, but Mr. Sizemore suffered a stroke on Feb. 18, which caused a brain aneurysm. He had been in a coma and on life support since then. Mr. Sizemore could be intense, charismatic and manic in roles as soldiers, thugs, cops, killers and, in a television movie, the baseball player Pete Rose. As Sgt. Mike Horvath in Steven Spielberg’s “Saving Private Ryan” (1998), he was the devoted second in command to Captain Miller (played by Tom Hanks) in a small group of Army Rangers whose mission after the D-Day invasion was to locate a soldier whose three brothers had already died in battle.Near the end of the movie, Horvath eloquently lays out the choices facing Miller: Let Private Ryan stay and fight, which he prefers, or send him home, as the unit had been ordered to do.“Part of me thinks the kid’s right — what’s he done to deserve this?” Mr. Sizemore, as Horvath, says. “He wants to stay here? Fine, let’s leave him and go home. But then another part of me thinks, what if by some miracle we stay, and actually make it out of here? Someday we might look back on this and decide that saving Private Ryan was the one decent thing we were able to pull out of this.” “That’s what I was thinking, sir,” he concludes. “Like you said, Captain, we do that, we all earn the right to go home.”Mr. Spielberg was not the only A-list director Mr. Sizemore worked with. In Oliver Stone’s “Natural Born Killers” (1994), he was an obsessed detective pursuing a young couple on a murder spree. In Michael Mann’s “Heat” (1995), he was a member of a crew of thieves led by Robert De Niro. And in Ridley Scott’s “Black Hawk Down” (2002), based on a botched United States military raid in 1993 in Mogadishu, Somalia, to capture lieutenants of a brutal warlord, he was the commander of the 75th Ranger Regiment.Mr. Sizemore in a scene from the television series “Robbery Homicide Division.” One critic said Mr. Sizemore was the main reason to watch the show.Tony Esparza/CBSWhen Mr. Sizemore starred on the television series “Robbery Homicide Division,” a police procedural set in Los Angeles and aired in the 2002-3 season, Robert Philpot of The Fort Worth Star-Telegram said he was the main reason to watch.“Using his oversized head, which hangs down slightly as if it were too heavy for his body, and his expressive eyes,” Mr. Philpot wrote, “Sizemore projects complete authority, keeping underlings as well as suspects in line.”Mr. Sizemore at the time was dealing with serious drug problems, which dated to the 1990s. Over the years he used heroin, crystal methamphetamine and cocaine, and he was in and out of rehab.“How long sober now?” Larry King asked him on his CNN show in 2010.“Three hundred twenty-six days,” Mr. Sizemore said.“What was the longest you were ever sober before that?” Mr. King asked.“A couple minutes,” Mr. Sizemore said. “No, that’s not true. I got sober in ’97 and was sober through 2002.”In 2003, he was convicted of physically abusing his former girlfriend, Heidi Fleiss, who in the 1990s ran an upscale prostitution ring and was referred to in the news media as the Hollywood Madam.In a letter to the judge who sentenced him, Mr. Sizemore wrote, “I am convinced that if I had not been under the influence of drugs, I would have controlled my behavior.”He served eight months in prison.In October 2004, he pleaded guilty to a felony count of possessing methamphetamine and was placed on probation. The probation was revoked in 2005 when he was caught using a prosthetic device to fake a drug test. His probation was later reinstated.And in 2007 he served several months in jail for violating his probation after being arrested in a hotel in Bakersfield, Calif., for possessing methamphetamine.“God’s trying to tell me he doesn’t want me using drugs because every time I use them I get caught,” Mr. Sizemore said in a jailhouse interview with The Associated Press.He participated in 10 episodes of the reality series “Celebrity Rehab With Dr. Drew” from 2010 to 2011, along with Ms. Fleiss, the former basketball player Dennis Rodman, the actress Mackenzie Phillips and others.In an article in The New York Times Magazine in 2009 about the series, Chris Norris wrote that Mr. Sizemore had fallen “from an Olympus populated by Pacino, De Niro, Spielberg and Scorsese to this beige-carpeted, cable-only Hades.”Mr. Sizemore played the Mafia boss John Gotti in the two-part 1998 TV movie “Witness to the Mob.”Thomas Edward Sizemore Jr. was born on Nov. 29, 1961, in Detroit. His father was a lawyer. His mother, Judith (Schannault) Sizemore, worked for the City of Detroit’s ombudsman.After graduating from Wayne State University in Detroit with a bachelor’s degree in theater in 1983, he earned a master’s in the same subject from Temple University in 1986. Three years later, he made his debut on television, in the series “Gideon Oliver,” and on film, in “Lock Up,” starring Sylvester Stallone.“Lock Up” was a flop, but United Press International wrote that Mr. Sizemore, as a “whacked-out scheming loser of an inmate,” had emerged “with semi-star potential.”By the time “Lock Up” was released, he had filmed parts in the forthcoming films “Born on the Fourth of July,” directed by Mr. Stone and starring Tom Cruise; “Blue Steel,” with Jamie Lee Curtis; and the dark comedy “Penn & Teller Get Killed.”“Most of the characters I play are losers, like the convict Dallas in ‘Lock Up,’” Mr. Sizemore told U.P.I. “In ‘Born on the Fourth of July’ I’m a quadriplegic. In “Penn & Teller,’ I’m a crazed killer. In ‘Blue Steel,’ I’m a crack maniac.”His role as a mobster in “Witness Protection” (1999) earned him a Golden Globe nomination for best performance by an actor in a made-for-TV movie or mini-series. That year, he and eight other actors from “Saving Private Ryan” were nominated for a Screen Actors Guild Award for outstanding cast.Mr. Sizemore continued to play characters on either side of the law, and despite his substance abuse problems, he remained busy for the rest of his career. He portrayed an internal affairs investigator on five episodes of “Hawaii Five-O” in 2011 and 2012; a C.I.A. agent assigned to rescue three American journalists taken hostage in “Radical” (2017); and a commander in the science fiction film “Battle for Pandora” (2022).And in a preternaturally chilling role, he played a depraved building manager who is tried for kidnapping and killing a little boy in a 2015 episode of “Law & Order: Special Victims Unit.”Mr. Sizemore in 2022. Despite his substance abuse problems, he remained busy until the end. Gonzalo Marroquin/Getty ImagesMr. Sizemore is survived by his mother; his twin sons, Jagger and Jayden; his brother Paul; his half sister, Katherine Sizemore; and his half brother, Charles Sizemore. His brother Aaron died last year. His marriage to Maeve Quinlan ended in divorce.During his 2010 interview with Mr. King, Mr. Sizemore said that soon after he had become successful in Hollywood, he started using cocaine with a famous actor, whom he would not identify.“I didn’t want to do it,” he said, “but there was people in this room and he did it, and I went, ‘If he did it, I’m going to do it.’ And I did it, it took a couple minutes and I went, ‘Wow, that is bomb. Where do you get that? Do you have any more of it?’” More