#1 The Orions
Was there any doubt that the Orions would be first on our list? The Orions are the most famous green Star Trek species, and for good reason. Whenever someone talks about Captain Kirk seducing alien women you think of Kirk in the embrace of an Orion.
The Orion females give off very strong pheromones that make them irresistible to the males of many species. Other than their green skin and pheromones however the Orion females don’t look much different from humans. The Orion males are similar to humans, but usually much more muscular.
The Orions are often involved in piracy, slavery, and espionage in Star Trek. The Orion female’s ability to use pheromones to manipulate the males of other species plays into these less than reputable lines of work.
When you think green alien you think Orions, and that’s why the Orions sit at the top of our list.