Setting--The Alpha Quadrant.

Star Trek. The show that started it all, as the crew of the USS Enterprise boldly went where no one had gone before. And when they got there, there were races bent on seeing the destruction of the Federation.

There are only four races that fit the description of being hostile seen in Star Trek. Two of those, the Romulans and the Klingons, have since appeared in all the other Star Trek series since. However, I am putting them here because this is where they had their debut. And besides for a brief war with the Federation in Deep Space Nine, it is the only series that the Klingons have been a hostile race.

• The Gorn
• The Klingons
• The Romulans
• The Tholians