Jane Fonda had an interesting guest at her birthday dinner last night ... Ted Turner ... the same guy she DIVORCED more than a decade ago ... and TMZ has the video to prove it. 

Fonda -- along with her BF Richard Perry -- was celebrating birthday number 75 at Craig's in West Hollywood ... and for some reason, ex-husband #3 got a spot at the table.
 
In fact, Fonda and Turner even left together in the same car (don't worry, Perry was in the car too).

Fonda and Turner's ten-year marriage ended in 2001 ... after Jane converted to Christianity without discussing the move with her husband first. Ted said he was hurt by the fact she would make such a big life decision without including him.

But the two reunited at a charity event back in October -- with Jane announcing that Ted was her "favorite ex-husband" ... adding, "I love you. I respect you. I admire you.”