Star Trek overlapped with the original Outer Limits to a remarkable extent. This was because they shared studio connections through the production company DesiLu. There were other reasons, connected to common interests in humanism amongst the producers, and through connections to Esalen and the various talks and activities held there which also included Star Trek alumni.
For these reasons and also because of the prolific nature of casting in episodic television, there are a lot of Star Trek recognizable faces throughout the Outer Limits.
Maintaining this tradition quite deliberately, the revival series cast as many Star Trek alumni as it could from the more recent series in the 1990s.