Muldaur just turned 84 and hasn't been in the limelight in ages but I wouldn't mind a cameo or even expanded mutliepisode appearance by Katherine Pulaski. She's neither my favorite Starfleet Doctor nor did she deserve the dislike she frequently got for Season 2 of TNG. She got more substance across 22 episodes of TNG than Dr. Crusher arguably did across the other 156.