Who is the actor from The Unit who died?

You're likely thinking of Dennis Haysbert, who played the role of Sergeant Major Jonas Blane on the CBS drama "The Unit".

Dennis Haysbert is still alive and well. He has continued to act in movies and TV shows since "The Unit" ended in 2009.

It's possible you are thinking of a different actor from the show or perhaps a different show altogether. Could you give me more details?