It seems that only two official Mission Impossible board games have been published through the years. Here's a brief look at each of them, along with an unofficial spoof card game.
Mission Impossible Game
Published by Ideal in 1966.
For 2 to 4 players.
I believe this is the first Mission Impossible board game ever published. One description makes it sound like a race game with players each starting in a corner of the board and using a spinner to determine how far they move (1 to 6 spaces). "Road Block" and "Mission Impossible" cards are used.
Published by Seven Towns and Berwick's Toy Co. in 1975.
For 3 to 6 players.
Players compete to discover the identity of their target and eliminate him in this board game. The game system is very advanced for a 1975 game, featuring hidden identities and a strong incentive to eliminate other players so that you're in a better position when it comes down to the final two. I believe this was published in Britain.
Published by Steve Jackson Games in 2006.
For 2 to 8 players.
Scheduled to be published in August 2006, Munchkin Impossible is a card game. According to the Steve Jackson Games web site, "The Munchkins are now spies... eliminating the opposition, playing with self-destructing gadgets, and changing loyalties even faster than they change hats."