Lamar Odom's father -- who's had numerous battles with Lamar -- just arrived at Sunrise Hospital in Las Vegas.
Joe Odom lives in the L.A. area, but arrived in Vegas Wednesday morning. He joins Khloe, Kim, and Kris Jenner on the short list of people who've been allowed access to see Lamar since he arrived at the hospital.
Lamar and Joe have been at odds for years -- over the Kardashians and Joe's own addiction issues -- but they eventually squashed their beef.
As TMZ reported ... Lamar has a 50/50 shot at surviving, we're told he's suffered several strokes and has multiple organs failing. Brain damage is a distinct possibility.