Classic Flash
CLassic Flash-Barry Allen is the fastest man alive, and the second speedster to be called the Flash.after getting struck by lighting he gained the power of super speed. Using his powers, he taps into the Speed Force and becomes a costumed crime-fighter. His weakness is subzero temperatures. His first appearance was in Showcase #4
Jay Garrick
Jay Garrick-The first in a long line of super-speedsters, Jay Garrick is capable of running at velocities near the speed of light as the Flash. A kind and dedicated scientist, Garrick has also served as mentor to other speedsters, and to many heroes over several generations. His first appearance was in Flash Comics #1
Black FLash
The Black Flash fulfills the role of grimmreaper for those who possess super-speed, returning them to the source of their powers: the Speed Force. His first appearance was in The Flash Volume 2 #138
Reverse Flash
Reverse Flash-Professor Eobard "Zoom" Thawne, otherwise known as the Reverse-Flash, was a curator of the Flash Museum from the 25th Century who was obsessed with Barry Allen, the Flash. Having turned himself into a speedster, Thawne desired to follow in his hero's footsteps, until he discovered that his destiny was to become the reverse. Giving into fate, Thawne made it his life's work to ruin Barry's until he learned to appreciate him. Trapped in an endless cycle of death and rebirth, Thawne's hatred kept growing, his personal timeline forever interwined with that of the man who is both his nemesis and his idol. His first appearance was in The Flash Volume 4 #40
Wally West
Wally West-Flash Wallace Rudolph "Wally" West is the fastest man alive, and the third speedster known as the Flash. Using his superspeed powers, he wields the Speed Force and becomes a costumed crime-fighter. His first appearance was in Justice league volume 2 #50
Injustice Flash
Injustice flash is very similar to the classic flash except on his world he joined Superman’s regime taking over the world, and is one of the only members of the Justice that eventually turned against Superman and sided with Batman’s insurgency. His first appearance was in the video game injustice gods among us by netherrealm studios.
Red Death
Red death-Barry Allen of earth -52 was friends with Batman of his world until many of Wayne's sidekicks died, causing Batman to go insane. Batman thought that, if he had the Flash's power, he'd be fast enough to stop crimes that he otherwise could not. After forcing Barry into the Speed Force with him, Batman having bested the Flash, the resulting energy caused the two superheroes's bodies to turn into skeletons and as such, the Flash was ultimately and permanently fused into Batman's body, and Wayne now had the super-speed he had so desperately craved. His first appearance was in Batman:The Red Death #1
Kingdom Come Flash
Kingdom come Flash-Wally west of earth 22 served as a hero for many years, calling himself "the Flash". After Superman retired, the Flash remained a hero, but he stopped... stopping. He began running instantly from crime scene to crime scene, disaster to disaster, until he became a gale force, patrolling Keystone City at speeds no human could follow. His first appearance was in Kingdom Come #1