Born in Bridgeport, CT, Dennehy was raised by his father, Edward, a correspondent and editor for the Associated Press, and his mother, Hannah, a former nurse. He spent his adolescence and teen years in Brooklyn, where his broad frame was put to good use on the football team of Chaminade High School. But a teacher encouraged Dennehy to act, which led him to tackle the lead role in Shakespeare's "Macbeth" while still in high school. He next attended Columbia University on a football scholarship, where he earned a bachelor's degree in history before enrolling at Yale University and studying drama. In 1959, Dennehy began active duty in the Marine Corp, and served overseas in Okinawa, Japan, in 1962. But after returning home, he began to boast that he had in fact served in the Vietnam for five years and suffered minor shrapnel wounds. For decades, Dennehy repeated his claims in interviews and even postulated on the horrors of war. Eventually, he was found out when the book, Stolen Valor (1998), was released, which had made mention of Dennehy's alleged service. When newspapers came calling, Dennehy finally recanted his claims and issued an apology for his actions, stating that he was unable to find a way to convey the truth.After his service in the Marines, Dennehy returned to the States and worked a string of jobs, including a stint as stockbroker with the same firm that employed Martha Stewart - the two remained close friends and Dennehy later appeared as a character witness in her insider trading trial - while appearing in community theater and off-Broadway in numerous productions. He made his professional debut in Anton Chekhov's "Ivanov," while making his first New York stage appearance in "Streamers" (1976). Of course, screen roles were not that far off and Dennehy made his feature debut in the sports comedy "Semi-Tough" (1977), starring Burt Reynolds and Kris Kristofferson, and that same year he had a significant supporting role in the small screen horror thriller, "It Happened at Lake Wood Manor" (ABC, 1977). After playing the partner of a San Francisco detective (Chevy Chase) in the comedic mystery, "Foul Play" (1978), Dennehy co-starred opposite Sylvester Stallone and Rod Steiger in the Teamsters-themed "F.I.S.T." (1978) and had his first starring role on a television series, playing a veteran house detective who solves crimes at an Atlantic City casino with his 13-year-old son (Doug McKeon) on the short-lived "Big Shamus, Little Shamus" (CBS, 1979). Because of his substantial presence on screen, Dennehy began landing supporting roles with considerably more heft, playing a sergeant in the Vietnam drama, "A Rumor of War" (1980), based on the best-selling novel of the same name. Meanwhile, his stage work continued to gain critical attention, and his appearances on screen soon culminated with his breakout performance as a small-town lawman and sadist who regrets his decision to hassle Vietnam Vet John Rambo (Sylvester Stallone) in "First Blood" (1982). His blend of bone-deep badness and folksy charm caught the attention of casting agents and producers, who busied the next few years of Dennehy's life with a variety of roles, often as characters in positions of authority. He was the offbeat bush pilot who deposits Charles Martin Smith in the Alaskan wilderness in "Never Cry Wolf" (1983) and played the New York detective who aids a Soviet policeman (William Hurt) hunt down a serial killer in the moody "Gorky Park" (1983). He next delivered one of his best performances, playing a casually cruel lawman who has it in for a disparate outlaw (Kevin Kline) in Lawrence Kasdan's retro Western, "Silverado" (1985). Dennehy followed with a memorable turn as the bemused alien leader in Ron Howard's heart-warming sci-fi drama, "Cocoon" (1985), starring Steve Guttenberg and Wilford Brimley.At the time, Dennehy also earned a few rare leads, most notably as a wisecracking cop who aids Bryan Brown's special effects whiz in the critically acclaimed thriller "F/X" (1986), and a rough-hewn driver in Africa who romances Brooke Adams in "The Lion of Africa" (HBO, 1986). After a supporting turn as a dogged police detective in "Legal Eagles" (1986), he garnered further acclaim as a famed American architect who physically and emotionally unravels in Peter Greenaway's challenging drama, "The Belly of an Architect" (1987). Next he more than held his own against raging hitman James Woods, who shares his experiences with Dennehy's inquisitive police detective-turned-author in John Flynn's underrated psychological thriller, "Best Seller" (1987). After appearances in minor films like "Miles from Home" (1988) and "The Man from Snowy River II" (1988), Dennehy made a cameo appearance at the end of the much less successful sequel, "Cocoon: The Return" (1988). Meanwhile, Dennehy continued to appear on the small screen, most notably as General Leslie Groves, the military representative during the creation of the atomic bomb in the Emmy-winning television movie, "Day One" (1989). More plum movie assignments soon followed for Dennehy, including a role as Harrison Ford's boss in "Presumed Innocent" (1990) and a showy bit as a crooked boxing promoter in "Gladiator" (1992), for which he dropped 35 pounds. Dennehy next chilled television audiences as serial killer John Wayne Gacy in the suspenseful Canadian-made miniseries "To Catch a Killer" (Bell Media, 1992), which brought him an Emmy nomination for Outstanding Lead Actor. He scored several more times in roles based on true-life personalities, including union leader Jackie Presser in "Teamster Boss: The Jackie Presser Story" (1992), as a lawyer involved in the Charles Starkweather murder spree in "Murder in the Heartland" (1993), which brought him another Emmy nod, and as a polygamist cult leader in "Prophet of Evil: The Ervil LeBaron Story" (1993). Amidst all these sinister characters, Dennehy charmed audiences in "Foreign Affairs" (1993), a gentle period romance with Joanne Woodward, while he managed to show off his comedy skills - as well as song and dance moves - in what was arguably his most popular film, the Chris Farley/David Spade comedy gem, "Tommy Boy" (1995), in which, although he had limited time onscreen after dying in act one, his presence as Tommy Boy's (Farley) beloved father was felt throughout the film. The actor grew very close to his onscreen son, doing his best to help the troubled comic before Farley's untimely overdose death in 1997. Also at the time, Dennehy made the first of several popular television movies starring as tough cop Jack Reed in "Deadly Matrimony" (NBC, 1992). Over the next few years, Dennehy returned to the role four times, serving as writer and director on each of the productions, including "Jack Reed: Badge of Honor" (NBC, 1993), "Jack Reed: A Search for Justice" (NBC, 1994), "Jack Reed: A Killer Amongst Us" (NBC, 1996) and "Jack Reed: Death and Vengeance" (NBC, 1996). After making his Broadway debut in a production of Irish playwright Brian Fiel's "Translations" (1995), Dennehy scored as the avuncular head of the Montague clan in Baz Luhrmann's unorthodox feature adaptation of "Romeo + Juliet" (1996). He also starred in, wrote and directed the TV movies "Shadow of a Doubt" (1995) and "Indefensible: The Truth about Edward Brannigan" (1997). In 1998, Dennehy returned to the stage in Chicago for the 50th anniversary production of Arthur Miller's "Death of a Salesman." The production was a critical and box office hit, eventually making its way to Broadway for even more applause, as well as a Tony and Olivier Award for Dennehy's moving portrayal of the universal working man, Willy Loman. A 2000 television movie version, which Dennehy co-produced, brought him Golden Globe and Screen Actors Guild awards, as well as an Emmy nomination atop further acclaim.Dennehy went on to executive produce the Western "The Warden of Red Rock" (2001) and "Three Blind Mice" (2001), the latter of which was based on the popular detective procedural novel by Ed McBain. He next served as executive producer on one of his few forays into a weekly television series, "The Fighting Fitzgeralds" (NBC, 2001), on which he starred as a New York firefighter whose large and combative family prevented him from enjoying his retirement. Despite decent reviews, the show's network run was short-lived. Undaunted, he continued to contribute rave-worthy performances on television, including a turn as controversial college basketball coach Bobby Knight in "A Season on the Brink" (ESPN, 2002), and as Helen Mirren's husband, whose illness forces her to take a lover, in the small screen remake of "Tennessee Williams' The Roman Spring of Mrs. Stone" (Showtime, 2003). Dennehy found some success on regular television by making semi-regular appearances on the sitcom "Just Shoot Me!" (NBC, 1997-2003), starring this time as "Tommy Boy" cohort David Spade's onscreen father. In 2003, Dennehy brought home a Tony Award for his performance in Eugene O'Neil's "Long Day's Journey into Night," which, like "Salesman," first staged in Chicago.Dennehy soon picked up his busy television schedule after its theatrical run with several impressive movies, including "The Exonerated" (Court TV, 2003), and "Our Fathers" (Showtime, 2005) which focused on the sex scandals that rocked the Catholic Church; the latter earned the actor another Emmy Award nomination. Back in features, he had a supporting role in Spike Lee's "She Hate Me" (2004), and co-starred opposite Ethan Hawke and Laurence Fishburne in the remake of "Assault on Precinct 13" (2005). After a guest starring role as a Republican senator on "The West Wing" (NBC, 1999-2006), Dennehy took on another challenging role on Broadway as Matthew Harrison Brady, the fundamentalist lawyer who battles with a thinly disguised Clarence Darrow in the classic play, "Inherit the Wind" (2006). He also added voiceover actor to his long and varied list of credits with performances as Babe Ruth in the little-seen animated film "Everybody's Hero" (2006) and as the father of an aspiring chef in Pixar's "Ratatouille" (2007). After co-starring with Chazz Palminteri in the indie thriller "10th and Wolf (2007), Dennehy played yet another cop in "Righteous Kill" (2008), starring heavy hitters Robert De Niro and Al Pacino. He next played the father of an unassuming school teacher (Russell Crowe) who hatches a plan to break his wife (Elizabeth Banks) out of prison after she's wrongly accused of murder in "The Next Three Days" (2010). Dennehy's prolific pace slowed in the 2010s, with small performances in films like Terence Malick's experimental "Knight of Cups" (2015) and an adaptation of Anton Chekov's "The Seagull" (2018) being his most high-profile roles. Dennehy's final screen role came in the indie comedy "Tag" (2018), followed by a recurring role in crime drama "The Blacklist" (NBC 2013-). Brian Dennehy died on April 15, 2020 at the age of 81.