Jason Wingreen passed away on December 25, 2015 at the age of 95. In lending his voice to just four lines of dialogue in Empire Strikes Back, Wingreen helped make bounty hunter Boba Fett one of the most enduringly popular minor characters in the Star Wars movies. I remember when we learned only in 2000, from the Star Wars Insider, the name of the uncredited actor who voiced him (we only knew that Boba Fett was physically played by Jeremy Bulloch and some stunt men); Wingreen later said this generated a lot of fan mail and changed his life. It spoke to his talent that he was able to use a voice that perfectly matched Boba Fett’s strong, mysterious, vaguely Western appearance, and make it memorable.
Comicbook.com has a short article and a Youtube video of all of his lines in the original Empire Strikes Back (thank you!): http://comicbook.com/2016/01/02/jason-wingreen-voice-of-boba-fett-has-died/