Morok

The Moroks were a humanoid race who founded their own empire. However, like all great empires, they soon fell into decline.

History
The Moroks set up a Space Museum on Xeros to celebrate their victories. They killed many Xerons, leaving only the children alive, who were then sold into slavery when they were old enough. The First Doctor and his companions aided the Xerons in their revolution against the Moroks. They killed the Museum's curator, Lobos. With the planet free, the Xerons destroyed the Museum. (TV: The Space Museum)

The Monk was once a technical adviser to the Moroks. (PROSE: No Future)

The Morok Empire collapsed in the 30th century due to human intervention. (PROSE: The Death of Art)

While holding an auction for the Face of Humanity, Fegovy created the holographic illusion of two Moroks to increase the sale price. (PROSE: Fegovy)

The Xaranti ship that invaded Earth in the 1970s was a modified Morok battlecruiser. (PROSE: Deep Blue)

Geoffrey Vantage asked if the Skythros Warpshock was "the last word in super-luminary style or the last word in looking like a total Morok". (AUDIO: Max Warp)

Alternative Timeline
In an alternate timeline where the Sixth Doctor died in the Matrix during a fight with the Valeyard, the Moroks held Melanie Bush prisoner during her search of the Valeyard. (AUDIO: He Jests at Scars...)

Behind the scenes

 * Amongst other things, the documentary Defending the Museum explored Robert Shearman's view that the Moroks were intended to parody the quintessential Hartnell-era foes. He evidenced this by suggesting Morok to be a spin on "moron" and examined their dull-witted behaviour.
 * The Dalek Handbook suggests that the Moroks visited the Dalek City on Skaro some time after the events of The Daleks and collected a Dalek casing for their museum. Their expedition also managed to restore power to the city, leading to the revival of the Daleks. However, this is only a suggestion and the handbook also notes that Thals or explorers from Earth could have been responsible for restoring the power instead.