EXCLUSIVE

Windell D. Middlebrooks -- the actor best known for playing the straight-talking Miller High Life delivery man -- died suddenly at his home ... TMZ has learned.

Sources close to Middlebrooks tell us he was found unconscious at home in the San Fernando Valley Monday morning -- and was transported by ambulance to a hospital ... where he was pronounced dead.

We're told it does not appear there was any foul play.

While he was best known for the Miller commercials ... Middlebrooks was also a very successful TV actor with roles on "Cougar Town," "Parks and Rec," "Scrubs," "It's Always Sunny In Philadelphia," and the "Bernie Mac Show."

He was also a series regular on ABC's "Body Of Proof."

Middlebrooks was 36 years old.