Martians

Martians are an alien species that live on the planet Mars. They have between one and three eyes.

History
During the Stonecutters' song "We Do", just after Lenny sang "Who keeps the Martians under wraps?", a Martian was seen at the table singing with the Stonecutters.

A Martian was in the audience as Kang and Kodos warmed up the crowd by telling a few jokes.

In 2039, Homer and Marge went to Mars with Martian Vacations. They adopted a Martian in late 2039 or early 2040, which appeared with them the next year.

A number of Martians planned to invade Earth, coincidentally while Pod People and Venusians were also invading. However, after a Robot Ghost Clone from the future revealed its plan to shoot everyone twice, the Martians surrendered.