At Toronto Trek '76 I saw Mark Lenard, George Takei, Walter Koenig, Nichelle Nichols and Grace Lee Whitney. Very cool. In later years I got to see Nichelle Nichols again, but the rest of the actors I've seen were non Trek performers: Claudia Christian, Jerry Doyle, Christopher Judge, Andreas Katsulas. I also got to meet and speak with John Colicos and later Leni Parker from Earth Final Conflict.
I also got to meet and speak with several times over the years with Canadian SF writer Robert Sawyer. We got a bit chummy and exchange messages every so often. Sawyer is a HUGE TOS fan.