Born in Detroit, MI, Sizemore was raised by his father, Thomas, a lawyer and psychology professor, and his mother, Judith, who worked for an urban ombudsman. After attending Michigan State University for a year, he earned his bachelor of fine arts in theater from Wayne State University. Sizemore went on to earn his master's in theater from Temple University, before moving to New York City in order to start his acting career. He amassed onstage credits in regional and off-Broadway productions before making his feature debut as a glib con who befriends Sylvester Stallone in the slammer in "Lock Up" (1989). He was next tapped by director Oliver Stone to play an angry wheelchair-bound vet opposite star Tom Cruise in "Born on the Fourth of July". Sizemore made career strides on the small screen as well, appearing as a guest star in the pilot episode of the short-lived drama, "Gideon Oliver" (ABC, 1989), before landing a recurring role as Sgt. Vinnie Ventresca, aka The Dog Man, the love interest of Colleen McMurphy (Dana Delany) on "China Beach" (ABC, 1988-1991). Sizemore's spontaneity and robust humor allowed him to develop an intense, fast-talking persona for many of his characters - typically cops or cons on the fringe - that raised his performances above a more clichéd direction other actors of lesser talent may have taken. In the early 1990s, he began landing roles that allowed him to turn in several memorable performances. After a supporting role as a bank executive involved in drug dealing in "Harley Davidson and the Marlboro Man" (1991), he starred opposite Sharon Stone and Dylan McDermott in the crime thriller "Where Sleeping Dogs Lie" (1991). In "Passenger 57" (1992), Sizemore played an airport manager who aids an anti-terrorism expert (Wesley Snipes) in trying to save hostages aboard a hijacked airliner. He stood out among a cast that included Dennis Hopper, Christopher Walken and Gary Oldman in "True Romance" (1993), playing a wisecracking cop alongside his more staid partner (Chris Penn), who tries to get a socially awkward comic book store clerk (Christian Slater) and his ex-hooker girlfriend (Patricia Arquette) to bust a big Hollywood producer (Saul Rubinek) with a suitcase full of cocaine. In "Hearts and Souls" (1993), Sizemore had a more substantial supporting role as the amiable, but tough guardian angel of Robert Downey, Jr.Sizemore also registered as a stolid Bat Masterson allied with Kevin Costner's "Wyatt Earp" (1994) and expanded his rep playing an obsessive and deranged detective on the trail of a murderous couple (Woody Harrelson and Juliette Lewis) for a reteaming with director Oliver Stone in "Natural Born Killers" (1994). He remained busy the following year with "Devil in a Blue Dress" (1995), which found him playing an enigmatic fixer who draws P.I. Easy Rawlings (Denzel Washington) into a dangerous case. After playing a sleazy private investigator opposite Ralph Fiennes and Angela Bassett in "Strange Days" (1995), Sizemore was part of a hard-hitting armed robbery crew led by a career thief (Robert De Niro), who meet their match when an unflinching LAPD detective (Al Pacino) tries taking them down in Michael Mann's excellent "Heat" (1995). Following the completion of "Heat," Sizemore's longtime addiction to drugs became public knowledge after De Niro staged an intervention that resulted in Sizemore entering a rehabilitation clinic. Later, Sizemore publicly credited De Niro for helping him overcome a drug habit, which in hindsight, proved to be only temporary. In the meantime, he managed to land the lead as a slightly cynical cop investigating a mysterious murder at a Chicago museum in "The Relic" (1997). After packing on a few pounds, Sizemore offered a chilling portrayal of reputed mobster John Gotti in the miniseries "Witness to the Mob" (NBC, 1998), which was executive produced by De Niro. Later that year, he had one of his biggest breakthroughs playing Sergeant Hovarth, the loyal right-hand man of Captain John Miller (Tom Hanks) in Steven Spielberg's roundly acclaimed World War II epic, "Saving Private Ryan" (1998). The actor received exceptional notice for his multifaceted performance in the violent, yet spellbinding account of the rescue of the titular missing soldier (Matt Damon) from behind enemy lines. Sizemore next joined forces with Martin Scorsese for a scene-stealing performance as a wild ambulance driver opposite Nicolas Cage in "Bringing Out the Dead" (1999). He received additional acclaim and notice for his gripping turn in the original drama "Witness Protection" (HBO, 1999) as a gangster- turned-government witness whose family begins to disintegrate under the pressure of their new lives. Sizemore earned a Golden Globe nomination for Best Actor in a Miniseries. Keeping a steadily high profile, he was featured with the lead supporting role as a fight promoter in Ron Shelton's "Play It to the Bone" (1999), a boxing film pitting two fighter friends (Woody Harrelson and Antonio Banderas) against each other in the ring.Continuing a busy career, Sizemore co-starred with Val Kilmer in the sci-fi thriller "Red Planet" (2000) while also appearing in the Scotland-set soccer drama "The Match" (2000). He followed up with two high-profile, top-grossing films that should have been a high point for his career, but instead marked the beginning of a long string of troubles born from his previous battles with drug addiction. In "Pearl Harbor" (2001), he was Sgt. Earl Sistern, while in "Black Hawk Down" (2001), he delivered a powerful performance as a Lt. Col. commanding the 3rd Ranger Battalion in the disastrous 1993 Battle of Mogadishu. He next landed a lead role as a LAPD captain in the CBS drama series "Robbery Homicide Division" in 2002 and co-starred with Morgan Freeman in the supernatural thriller feature "Dreamcatcher" (2003), playing a refreshingly heroic and untroubled role. Despite his steady workload in big movies, Sizemore had long battled personal demons that finally grabbed hold of him, turning the once prominent character actor into a cautionary tale of how one could squander fame and fortune through substance abuse.Sizemore had previously battled drug abuse and alcoholism while being accused by ex-wife, actress Maeve Quinlan, of spousal abuse in 1997. He made fresh headlines in 2003 when he was convicted of assault and battery for abusing his former fiancée, the infamous Hollywood madam, Heidi Fleiss. He was also convicted on several other counts, including harassment. Sizemore was required to enter a drug rehabilitation program during his trial, while being sentenced to six months in jail and three years probation. Adding insult to injury, he was sued for sexual harassment by a former personal assistant. In 2005, the actor was sentenced to 17 months in prison and four months in rehab for violating his parole conditions in March of that year. He was back in court again for allegedly trying to bypass a drug test with a fake prosthetic, not reporting to his probation officer, missing counseling sessions and not advising authorities of his new address. In early 2006, Sizemore violated his probation a second time by testing positive for drugs and getting expelled from a drug treatment program for fighting. He was sentenced to three years' probation and 90 days in lock-down rehab.While bouncing around from court to jail and back again, Sizemore kept feeding his habit by starring in a number of direct-to-DVD thrillers that the same actor would have scoffed at only a few years prior. With titles like "Furnace" (2006), "Zyzzyx Road" (2006) - which suffered the ignominy of earning just $30 at the box office - and "Stilletto" (2008), Sizemore's best days seemed far behind. He suffered perhaps his greatest humiliation in 2005 when over eight hours of Sizemore having sex with various women leaked over the Internet. But instead of disparaging the tape, a broke Sizemore complained that he earned no money from its release while his two children were still on welfare. Meanwhile, he was arrested once again in 2007 for possession of methamphetamines while at a hotel in Bakersfield, CA, which led to a nine-month prison sentence he managed to avoid. Two years later, he was arrested for an outstanding warrant, but was later released.Trying to get both his life and career back on track, Sizemore appeared in an episode of "CSI: Miami" (CBS, 2002-12) while landing a five- episode arc as a detective on the unfortunately short-lived "Crash" (Starz, 2008-09), starring Dennis Hopper. Following a guest starring appearance on "Southland" (NBC/TNT, 2009-13), he joined the cast of "Celebrity Rehab with Dr. Drew" (VH1, 2008-12), where he ironically talked about his addictions sitting across from Heidi Fleiss. He later joined Fleiss, former NBA star Dennis Rodman and rock singer Seth Binzer for "Celebrity Rehab Presents Sober House" (VH1, 2009-2010). Sizemore was caught trying to smuggle a crack pipe into the house during the first episode, while his proximity to Fleiss exacerbated conflict between the two (both signed consent forms prior to "Celebrity Rehab"). Meanwhile, Sizemore had a number of low-budget movies released, including "Chlorine" (2010), "C.L.A.S.S." (2010) and "White Knight" (2011). Following a stroke February 18, Tom Sizemore died on March 3, 2023 in Burbank, CA at the age of 61.