Xebel is the chief scientist of Dimension Aqua. He created the Dimensional Warp which allowed Mera and others to travel between their world and Earth. He was imprisoned under Leron's regime and presumably freed when the regime ended. Xebel last appeared in 1978. 
 
Curiously, Action Comics #539  (January, 1983) reintroduced Dimension Aqua under the name "Xebel". 

  

Powers & Abilities

Xebel shares several powers with Mera and other members of their race. Their world is covered entirely in water and their race are amphibians. Swimming is their equivalent to walking. Their main power is hydrokinesis (water control). They have the ability to psionically increase the density of volumes of water and shaping them to create hard-water constructs. He can use them to cause blunt force damage or simply drown opponents. He has low-level telepathic powers, allowing him to communicate with others. He can not perceive the thoughts of individuals not broadcasting to him. His main weakness is common to all his race. Lead causes them to loose their hydrokinetic powers for the duration of their exposure to it.