I was recently reminded that the same actor, Diana Muldaur, played blind human telepath Miranda Jones in TOS and Doctor Pulaski in TNG. Majel Barrett Roddenberry played Nurse Chapel in TOS and Lwaxana Troi (Counsellor Deanna Troi's mother) in TNG.
I'm well aware that TOS actors Leonard Nimoy, James Doohan, DeForest Kelly, and Mark Lenard (as Sarek) played the same characters on cameo appearances in TNG; of these, only Mark Lenard had played another character (most notably the first Romulan commander seen in the series, but apparently also one or two others), though Doohan voiced some puppets.
Which, if any, other actors from TOS played different characters in TNG-era series (including DS9 and Voyager) or movies?