An astute Aniston fan was able to ID Jennifer's mystery man from last night as actor Christopher Gartin!

Chris and Jen enjoyed dinner together yesterday evening at Jennifer's favorite spot -- The Terrace at Sunset Towers Hotel.

Not coincidentally, Gartin is a pal of Courteney Cox's -- in fact she even promoted him back in '08 by slapping this bumper sticker on her car!


Chris starred with Courteney's hubby David Arquette in the 1996 film Johns and apparently, a relationship developed from there. There was only one little bump in the road to bringing Chris and Jen together ... Chris' wife!

Gartin was married to Australian-born event planner Joanne, but since those two eventually divorced, Courteney was free to make the introduction to her hot friend Jennifer Aniston! (Not your average set-up!)

Buuuuut ... why was Jen so intent on getting past our lenses last night without being photographed? If Gartin were just a friend or business associate, I don't think she'd be hiding like that now would she???

Roll tape!