His wife, Malgosia Tomassi, confirmed his death in a statement to Variety on Wednesday, revealing that the veteran performer passed away on Tuesday following a prolonged battle with a serious heart condition and heart failure.
“After a long and difficult battle with a serious heart condition and heart failure,” Tomassi said.
Keach enjoyed a career spanning more than six decades, earning recognition for his versatility and ability to bring complex characters to life. From Shakespearean roles on stage to his memorable portrayal of hard-boiled detective Mike Hammer on television, he established himself as one of America's most respected performers.
His rise to prominence began in the mid-1960s when he made a strong impression on Broadway. His theatrical performances earned him praise as one of the country's outstanding Shakespearean actors, while his role in Indians brought him a Tony Award nomination.
Keach made his film debut in The Heart Is a Lonely Hunter, opening the door to a screen career that would eventually include more than 100 movies.
One of his most acclaimed performances came in John Huston's 1972 film Fat City, in which he starred alongside Jeff Bridges as a struggling boxer. His gritty and emotionally compelling portrayal earned critical recognition and further established his reputation as a serious Hollywood actor.
He also delivered notable performances in films such as Doc, where he portrayed legendary gunslinger Doc Holliday, The New Centurions and The Long Riders.
On television, Keach became particularly popular for playing the seasoned private investigator Mike Hammer in The New Mike Hammer. The character was based on the tough fictional detective created by crime novelist Mickey Spillane, whom Keach admired and later befriended.
However, his successful career experienced a major setback in 1984 when he was arrested at London's Heathrow Airport for attempting to smuggle cocaine concealed in a shaving cream can.
Reflecting on the incident in his autobiography, All in All, Keach openly acknowledged his mistake.
“Busted, like some common perp on ‘Mike Hammer.’ I knew how stupid I had been,” he wrote.
He subsequently pleaded guilty and served six months in Reading Prison in England, an experience that threatened to derail his career.
Despite the controversy, Keach eventually rebuilt his career, delivering another acclaimed performance as celebrated American writer Ernest Hemingway in the 1988 television miniseries Hemingway. The role earned him a Golden Globe Award.
He continued to attract new audiences in later years, particularly through his portrayal of New York's archbishop in the long-running CBS drama Blue Bloods. He also became familiar to television audiences through a recurring voice role in the animated series The Simpsons.
Keach's death marks the end of a remarkable acting career that moved effortlessly between classical theatre, Hollywood films and popular television, leaving behind a body of work that spanned generations.