Actor Powers Boothe died on Sunday afternoon at 68. The cause of death is still unknown.

POWERS BOOTHE DEAD AT 68

Boothe was a character actor who appeared in films like Sin City and Tombstone, and TV shows likes Deadwood, and Agents of S.H.I.E.L.D. His friend and fellow actor Beau Bridges tweeted out the news of Boothe’s death. “It’s with great sadness that I mourn the passing of my friend Powers Boothe,” he wrote. “A dear friend, great actor, devoted father & husband.”

Gary Sinise also chimed in on Twitter in tribute. “Lost a pal yesterday,” he said. “Powers Boothe was a wonderful actor, person & friends. Rest in Peace brother. I will miss you.”

The Texan actor began his career in the theater, playing a number of roles in Shakespeare plays. He made his Broadway debut in the late 1970s. In 1980, he won an Emmy award for Lead Actor in a Limited Series or Special for playing cult leader Jim Jones in CBS’ Guyana Tragedy. He won the award at the time of a actors’ strike, and said while accepting, “This may be either the bravest moment of my career, or the dumbest.”

Boothe was also nominated for two ensemble SAG Awards. He quickly gained a reputation for playing villains after playing Bill Paxton’s nemesis in Sudden Death, Senator Roark in Sin City and Cy Tolliver in Deadwood. He was also Gideon Malick in the Marvel Cinematic Universe in The Avengers, and later reprised the role in ABC’s Agents of S.H.I.E.L.D.

Additionally, he played Alexander Haig in Nixon (1995), a sheriff in Oliver Stone‘s U Turn (1997), and Curly Bill Brocius in Tombstone (1993). He had a brief stint on Nashville, and played both the Vice President and later the President on 24.

Actress Lea Thompson remembered her former Red Dawn co-star in a tweet: “I loved acting with you #powersboothe you were a gentlemen (sic) and a great actor #rip #RedDawn #Wolverines.”

Deadwood colleague Garret Dillahunt posted his condolences on Facebook. “RIP Powers Boothe,” he wrote.”This is when I knew him…on Deadwood. A formidable adversary, baseball lover and poser hater. Give em hell Powers.”