Former Buccaneers Running Back Doug Martin Dead at 36

Doug Martin -- a former running back who last played in the NFL in 2018 -- has died ... TMZ has learned.

A source with direct knowledge tells TMZ Martin passed away Saturday morning ... though they did not share any further details.

Martin was a standout RB at Boise State for four years before the Tampa Bay Buccaneers drafted him in the first round of the 2012 NFL Draft.

He played six seasons in Tampa Bay during which time he was twice named to the Pro Bowl and once received All-Pro honors. He finished his career in the 2018-2019 season with the then Oakland Raiders.

In his seven NFL seasons, Martin rushed for 5,356 yards and ran in 30 touchdowns. He racked up more than 1,200 receiving yards and a pair of receiving TDs as well.

We caught up with Martin once ... congratulating him shortly after he was drafted by the Bucs.

Martin was 36.