Oh, Man I love this topic! I'm always up for a Wing Commander sighting!
John-Ryhs Davies (Paladin) and Matthew Lillard (Mainiac) were in In The Name Of The King - A Dungeon Siege Tale.
Jason Bernard (Capt. Eisen) and John Spencer (Capt. Paulson, his replacement in WCIV) were in the movie Wargames.
Jeremy Roberts (Col. Dekker, WCIV and Prophecy) and Elizabeth Barondes (Panther, WCIV) were both in the Brisco County Jr. episode "Mail Order Brides"
Jeremy Roberts was with Jennifer MacDonald (Lt. Robin "Flint" Peters, WCIII) in the Brisco County Jr. episode No Man's Land.
I get the feeling the casting agent liked Brisco County Jr. Too bad Bruce Campbell was never in Wing Commander.
Peter Jason (Vice Admiral/Captain Daniel Wilford, WCIV and Prophecy) and Chris Mulkey (Hawk, WCIV and Prophecy) and were in the movies Dreamscape, 48Hours, and The Long Riders. They might tie Freddie Prince Jr. and Matthew Lillard for number of movies done together.
Peter Jason and Malcom McDowell were in the movie Sunset.
Peter Jason was with Mark Hamill (Blue Hair himself!) in the movie Village of the Damned.
Peter Jason and Tim Curry (the voice of Melek in WCIII, does that count?) were in Congo.
Chris Mulkey was with Courtney Gains (Lt. 'Radio' Rollins, WCIII) in Behind Enemy Lines.
Radio Rollins was reunited with Major Jace 'Flash' Dillon (Josh Lucas) in Sweet Home Alabama. My wife has that DVD. I may have to watch it again.
Malcom McDowell and Richard Riehle (Pliers, WCIV) were both in the Rob Zombie remake of Halloween II.
Richard Riehle and Chris Mulkey (Pliers and Hawk) reunite in the movie Mysterious Skin.
Richard Riehle and John Spencer were both in Black Rain.
I haven't even touched the cast of Privateer 2 yet. What others can y'all come up with?
And can anyone come up with a movie with three or more Wing Commander actors/actresses?
UPDATE: I HAVE MY THREE-BAGGER! Jurgen Prochnow (Xavier Shondi in Privateer 2 and Commander Paul Gerald in the Wing Commander movie), David Warner (Rhinehart in Privateer 2 and Admiral Tolwyn in the WC movie) and Peter Jason (Vice Admiral/Captain Daniel Wilford WCIV/Prophecy) were all in In The Mouth of Madness!