I suppose this really is a matter of opinion and taste, but memorable quality is probably a good barometer, too. I had a lot of trouble narrowing the list, but I did end up coming up with a top 5. Granted, these are rather subjective, but I think most people would agree that, at the very least, they are memorable. 1. Lt. Cmdr. Data, STAR TREK: THE NEXT GENERATION - Data, to me, is the reason I became a scifi fan. His curious nature, his constant search for ways to be more human, his heroic qualities... just some of the things that made him so memorable and loved. And I do make the argument that he embodies all the qualities of a hero. It's amazing how a character who has no emotion can spark a wide variety of emotions in others... just like Riker said once. Brent Spiner did a phenomenal job of bringing to life what could have easily turned out to be a dull creation. 2. Elim Garak, STAR TREK: DEEP SPACE NINE - Plain, simple Garak is anything but plain and simple. One of the best characters to ever be made in the STSR TREK franchise, you never knew what to expect with him. His background was a mystery. He never told the whole truth. But you couldn't help but be sucked in by his nature. The time that cemented him as a memorable character? The end of "THE WIRE" in season 2, when Bashir comments on all the conflicting stories and lies, and Garak simply said they were all true, "Especially the lies." Absolutely brilliant portrayal by Andrew Robinson. 3. G'Kar, BABYLON 5 - Brilliantly acted by the late Andreas Katsulas, his character had enormous growth from the beginning of the show to the end. He went through virtually every emotional turning point a single person can go through. 4. Londo Mollari, BABYLON 5 - It's almost impossible to think of G'Kar without Londo in the same sentence. These two were joined at the hip in multiple ways, and were equally memorable. His arc was in some ways the exact inverse of G'Kar, but Peter Jurasik played him with such ability that he could not be anything but memorable. 5. Scorpius/Harvey, FARSCAPE - FARSCAPE was FILLED with brilliant characters, and it is so hard to pick one. But I just realized there isn't a villain on this list. In my view, Scorpius is perhaps the best villain ever made. He had the one quality that is absent in almost all great villains... patience. His plans were such a slow burn, and he played such a long game. But they paid off a lot. And Harvey, inside Crichton's head, was just as memorable, if not more so. Some of the best scenes in the series had him. Wayne Pygram was excellent in this role. What about everyone else? I'd love to see what you think are the greatest characters in scifi tv.