Martians were a species from the planet Mars. They wanted to invade Earth and destroy humanity. They had teleportation technology, which left behind a green ichor when used, and ray guns.
The first time the Martians invaded, they used tripods. (PROSE: Enter Wildthyme, AUDIO: Vince Cosmos: Glam Rock Detective) Martians were able to disguise themselves as humans, but the disguises were not perfect as the Martians were still identifiable by their flashing silver eyes. (PROSE: The Ninnies on Putney Common, AUDIO: Vince Cosmos: Glam Rock Detective)
History
The first Martian invasion of Earth occurred in the 1890s. They used very strong-arm tactics — heat rays, and death machines, and trying to kill everyone. (PROSE: Enter Wildthyme, AUDIO: Vince Cosmos: Glam Rock Detective) Afterwards, during the reign of King Edward VII, they established an uneasy peace with Great Britain. Many in the British Empire were uneasy with allying with such recent would-be invaders, but it was generally thought slightly preferable to an alliance with the Germans. Mars' great scientists inspired a 1905 reorganisation of Russia's government into a paragon of rationality and enlightenment. Sherlock Holmes and Tom visited the Martian Embassy in Stepney.
However, the invasion and its aftermath was erased from history, along with Martian civilisation, by the action of The Book of the Enemy during the War in Heaven. After erasure from the timeline, its events were captured in the novel The War of the Worlds. (PROSE: The Book of the Enemy)
After humans settled and terraformed Mars, their fiction set on Mars became mundane, instead of imagining exotic Locals. Tripod Martians were among many fictional Martians smuggled onto the real Mars by Iris Wildthyme to start urban legends that would stimulate the human Martians' imaginations and keep the fictional worlds alive. (PROSE: Green Mars Blues) In the early 1950s, some Martians disguised themselves as various Parisian existentialists, including Simone de Beauvoir, Jacques Brel, and Marlene Dietrich. Iris Wildthyme and Dodie Golightly encountered these Martians in the Café Flore. (PROSE: The Ninnies on Putney Common)
In the 1970s, the Martians used more surreptitious means. They disguised themselves as public figures, particularly in the entertainment industry, so they could take over the minds of the humans. Vince Cosmos fought them, by trying to make the humans aware of them through his music, sending them back to their homeworld, and — when necessary — killing them. In 1972, Vince discovered that his manager, Arthur Corn, was a Martian. He stole Corn's map, which showed the locations of every Martian soul on Earth. (AUDIO: Vince Cosmos: Glam Rock Detective)
By 1979, Vince Cosmos was no longer popular, and decided to return to his home planet. Iris Wildthyme went to 1976 to steal the map from him, and gave it to Mida Slike, so that MIAOW could defend Earth from the Martians in his place. (PROSE: Hang onto Yourself)
Behind the scenes
The 1890s invasion by tripod Martians is obviously meant to be the one described in The War of the Worlds.