Reading the thread in the TNG forum about the series ending with "All Good Things.." as opposed to Nemesis made me wonder about the guest actors who appeared in Star Trek and could have carried a Star Trek series if given the opportunity (playing a role similar to that of Shatner, Nimoy, Kelley, Stewart, Spiner, etc., in terms of importance). Below is my list.
Mark Alaimo, Michael Ansara, Vaughn Armstrong, Casey Biggs, John Colicos, Jeffrey Combs, Bruce Greenwood, Bob Gunton, JG Hertzler, Famke Janssen, Penny Johnson, Dina Meyer, Ricardo Montalban, Tricia O'Neil, Eric Pierpoint, Christopher Plummer, William Sadler, Christian Slater, Susanna Thompson, Tony Todd, David Warner, Peter Weller, Paul Winfield
--Sran
Mark Alaimo, Michael Ansara, Vaughn Armstrong, Casey Biggs, John Colicos, Jeffrey Combs, Bruce Greenwood, Bob Gunton, JG Hertzler, Famke Janssen, Penny Johnson, Dina Meyer, Ricardo Montalban, Tricia O'Neil, Eric Pierpoint, Christopher Plummer, William Sadler, Christian Slater, Susanna Thompson, Tony Todd, David Warner, Peter Weller, Paul Winfield
--Sran