'Rock of Love' Star Kelsey Bateman Dead at 39

Kelsey Bateman -- a contestant on Bret Michaels' reality show 'Rock of Love' -- has died ... TMZ has learned.

A family sources tells us ... Kelsey passed away unexpectedly recently -- though it's unclear at this time exactly what caused her untimely death. We've reached out to local authorities for more information.

If you don't know "Rock of Love with Bret Michaels," it was a reality television show that ran from 2007 to 2009 ... and followed 25 contestants as they all vied to be Michaels' girlfriend.

Kelsey starred in the third and final season of the show -- titled "Rock of Love Bus with Bret Michaels" -- on which the ladies lived on tour buses and traveled with Michaels.

Kelsey made it all the way to the final nine women ... but was eliminated in dramatic fashion in the 7th episode.

Bateman showed up to the elimination drunk with several other contestants ... telling the cameras she laid on a speed bump and broke down in tears because of the pressures of the show before showing up to the elim.

Bret said he felt Kelsey's actions showed she simply wasn't making smart decision for herself before sending her back to Salt Lake City, Utah.

Bateman was 39.