Great Race of Yith (New)

In prehistoric Australia, the technologically advanced Yithians were attacked by the Flying Polyps. In order to escape, the Yithians transferred their minds far into the future. Unheroically, they traded places with a race of hive-minded insects, leaving them (undoubtedly confused) in the Yithians' old bodies in the midst of the Flying Polyp war, never to be heard of again.

Star-spawn of Cthulhu

Cthulhu's spawn are basically just smaller versions of himself. Some were trapped in R'lyeh when it sank, though many were not.