Trek guest actors in maybe surprising roles

[Kraig]

No, this person had a brief speaking role at the beginning of the movie.
He looked like a TOS actor, but i could be mistaken; however, I have seen him in other roles, the name just escaped me.

That leaves us with Jon Lormer: Though uncredited in Two on a Guillotine as a minister at a funeral, Lormer had multiple roles in the original Star Trek series. His appearances included:

Dr. Theodore Haskins in "The Cage" and "The Menagerie"

Tamar in "The Return of the Archons"

An old man in "For the World Is Hollow and I Have Touched the Sky"