Powers Boothe, best known for his role as Cy Tolliver on HBO’s critically acclaimed Deadwood, has died. He was 68.

Boothe died in his sleep of natural causes Sunday morning, his publicist confirms to TVLine. Word of his passing was first reported by actor Beau Bridges, who took to Twitter on Sunday afternoon to eulogize his “dear friend.”

It's with great sadness that I mourn the passing of my friend Powers Boothe. A dear friend, great actor, devoted father & husband. — Beau Bridges (@MrBeauBridges) May 14, 2017

Boothe first broke out as the title character in the 1980 miniseries Guyana Tragedy: The Story of Jim Jones, for which he won an Emmy award for Outstanding Lead Actor in a Limited Series or Special. From 1983 to 1986, he portrayed the title character in HBO’s Philip Marlowe, Private Eye. Eighteen years later, he returned to the premium cable network as part of the cast of Deadwood.

Following Deadwood‘s demise, Boothe kept busy on the small screen, first popping up in Season 6 of 24 as Vice President Noah Daniels. In 2012, he co-starred as Judge Valentine ‘Wall’ Hatfield in the limited series Hatfields & McCoys, and began a recurring role as father to Connie Britton’s Rayna James on primetime soap Nashville. Most recently, he recurred on Marvel’s Agents of S.H.I.E.L.D., portraying HYDRA leader Gideon Malick during Season 3.