Speed Demon

Speed Demon was a speedster member of the Squadron Supreme.

Avengers Assemble
In the episode "Terminal Velocity," Speed Demon infiltrates Stark Tower with a special speed belt where he gets Hulk trapped in the same speed frequency as he is while the other Avengers were fighting Hyperion. While evading Hulk, Speed Demon was able to download some specific information from the Stark Tower computers. After J.A.R.V.I.S. was able to detect Hulk's plight, Iron Man was able to help Hulk destroy the speed belt. While pursuing Speed Demon out into the ocean, Hulk was able to throw Speed Demon into Hyperion freeing the other Avengers from his vortex breath. Speed Demon was able to grab Hyperion as he gets away. Upon meeting with Nighthawk, Speed Demon gives him the information he gathered from the Stark Tower computers.

In the episode "Avengers' Last Stand," Speed Demon joins the Squadron Supreme in enacting Nighthawk's plot against the Avengers.

In the episode "Avengers Underground," Speed Demon's speed belt is taken from him as he ends up trapped in a cube cell as Hulk gets even with him from the previous incident. After the Squadron Supreme are defeated, Speed Demon and the rest of the Squadron Supreme are mentioned to have been remanded to a special section of the Vault.

Trivia

 * Speed Demon was based on DC's The Flash.
 * He was a reformed villain in the comics and is currently called Whizzer.
 * Speed Demon's voice actor Jason Spisak has already portrayed his inspiration Wally West/ Flash in Young Justice and JLA Adventures Trapped in Time.