The Original Series has the honor of playing 3 of Star Trek's most important alien species: Vulcan, Klingon, and Romulan.

The Next Generation took significantly more risks with its plot, characters, and overall storytelling proving that is superior to the original.

If you watch Star Trek shows a lot, like I do, you start to notice some familiar faces. With decades of television shows and movies under its belt, it's only natural that the franchise has approached actors to play multiple roles over the years.