Echo is a longtime member of the Legion of Super-Villains with the ability to control and project sonic waves. In the "Five Years Later" timeline of the Legion of Super-Heroes he was shown to have been a member of the LOSH for a short time.
Myke-4 Astor aka Echo was born on Khundish Calish-Aetia possessing destructive sonic powers. The Khunds performed brutal experiments on Echo to learn more about his powers, resulting in the physical disfigurement of Echo, which is why he has to permanently wear a respirator mask to survive.
Echo fled the oppressive Khundish Empire, and entered the United Planets with little concept of law and order. He joined a band of pranksters known as "The Demon Mother's Little Angels" who mainly vandalized Khundish Embassies and sabotaged Khundish diplomatic operations.
This lifestyle eventually led Echo to joining with more hardened criminals: the Legion of Super-Villains. Echo was a member of this team for many of their conflicts with The Legion of Super-Heroes and even for one battle with Superman and Batman.
However, in the "Five Years Later" timeline, Echo ended up instead joining the Legion of Super-Heroes, due partly to their shared animosity with the Khunds.
Echo first appeared in a story starring the Adult Legion of Superheroes when he was defeated by Cosmic Man.
In Echo's second appearance, he was shown in a flashback during the Legion of Super-Heroes's "Five Years Later" timeline as a member of that group.
In his third appearance, Echo was part of a Legion of Super-Villains squad who manipulated the timeline to alter the history of Superman and Batman.
In his fourth appearance, Echo joined Superboy Prime's Legion of Super-Villains to fight the Legions of three different worlds.
Powers and Abilities
Echo has the ability to project sonic emissions powerful enough to knock over walls and disable opponents. He has excellent control over these abilities.