Boothe's award win arrived in the midst of an actors strike and he chose to cross the picket line to accept his gong.
Reflecting on his triumph and the unusual circumstances surrounding it, he said at the time: "This may be either the bravest moment of my career or the dumbest."
Boothe - who married his college sweetheart Pam in 1969 and had two children, Parisse and Preston, with her - also received nominations for two ensemble SAG Awards, in 1996 for Nixon and again in 2007 for Deadwood.
In recent years, he has perhaps become better known as Gideon Malick in the Marvel Cinematic Universe.
Powers debuted the role in 2012's The Avengers and later reprised it to star in Agents of S.H.I.E.L.D.
He has also played the parts of former mayor Lamar Wyatt on Nashville, as well as Noah Daniels, the US President, on the hit TV series 24.
He also appeared in HBO's acclaimed western Deadwood.
- Bang! Showbiz