Bio: This insectile collective entity was, in the post-Crisis chronology, the proximate cause of the death of Abin Sur.
Angered by the Green Lantern Corps invasion of its homeworld, Tchk-Tchk, Legion went on a rampage through the universe to exterminate the Corps. They started picking off Lanterns one-by-one until they came upon Abin Sur. Though their battle was devastating, Sur found a way to escape. He crash-landed on Earth whereupon he died. His ring sought out a young Hal Jordan.
Jordan was thus Legion's new target. After a protracted battle that went all the way to Oa, Jordan eventually used the Central Power Battery to subdue Legion and return it/them to Tchk-Tchk.
Notes: This character has no relationship whatsoever with the Legion of Super Heroes.