Jonathan Frakes (STNG, Commander William T. Riker - directed 2 episodes of The Orville).
Marina Sirtis (STNG, Counselor Dianna Troy).
Robert Picardo (ST Voyager, "The Holographic Doctor")
Tim Russ (ST Voyager, Lieutenant Commander Tuvok).
Robert Duncan McNeill (ST Voyager, Lieutenant Tom Paris - directed 2 episodes of The Orville).
John Billingsly (ST Enterprise, Dr. Phlox).
Penny Johnson Jerald (ST Deep Space 9, Cassidy Yates-Sisko, Benjamin Sisko's wife - Plays Dr. Claire Finn and cast regular).
Brannon Braga (ST TNG, ST Voyager, ST DSN, Producer, Director, Writer, - directed 4 episodes of The Orville).
Jason Alexander (Seinfeld's George Castanza, and ST Voyager as Kurros, Plays the Bartender on The Orville).
Patrick Warburton (Seinfeld's David Puddy, Played Security Officer Tharl on The Orville).