Horror Express with Peter Cushing and Christopher Lee, which I’ve never seen. William F Nolin, who did Logan’s Run, wrote a version, but it was never filmed. Couldn’t really find any others, but I’m sure there are.
I also just found out tonight that there’s a fan film called The Thing Returns that looks so terrible I have to see it.
Also, there’s The Thing video game for PS2, Xbox, and Windows. Carpenter apparently considers it to be a canon sequel and the events in it clarify what happens at the end of the first movie.