The Flash

Eobard Twane is known as The Reverse Flash and also goes by the name Professor Zoom, he was created by John Broome and Carmine Infantino and made his first appearance in The Flash (Vol 1) issue 139 in 1963.
Eobard Twane is from the 25th Century and was a big fan of The Flash/Barry Allen and copied the way Barry Allen got his super speed and even changed his face to look like Barry, he then travel's back in time to met him when he see's the Flash museum and when he goes in he see's that one of The Flash's greatest foes is The Reverse Flash aka Eobard Twane who is a older version of himself this turns Eobard nuts turning him into a bad guy cause and effect if you will. The Flash would then later fight him, wipe his memory and send him back to his own time. He would later turn up again through The Flash history and even killing Barrys wife Iris West, The Flash is so upset that he snap's his neck in two this would force The flash to go on the run in to the future where some how Iris West life force is transfered into another body and Barry and Iris in the far future would have twins.
The Flash would then come back to the present where he lost his life in Crisis On Infinite Earth's this would then force Kid Flash aka Wally West to become the new Flash.
Eobard Twane would return again by pretending to be Barry Allen by changing his face again to look like him at first Wally West was pleased to have his uncle till Eobard started acting nasty forcing Wally West to give up being The Flash he later finds out that his not really Barry Allen but Eobard Twane Wally West ends up beating in because Eobard was always faster then Wally and because Wally thought he could never live up to Barry Allen he ends up beliving in himself taping into the speed force becomes even faster and beats Barry Allen.
Eobard would disappear again from comics and would reappear in The Flashpoint storyline which will be used in the Tv series and also Flash Rebirth which bought about the return of Barry Allen he wasn't actually dead but was in the speed force which gives all the flash's there powers.
There is also another link with the Allen and Twane family, when Barry was born he actually had a twin brother but the doctor gave the twin to another family because of mistake he made with being drunk resulting a couple losing there baby, the couple would name the bay Malcolm Twane who would also become a bad guy with super powers called Cobalt Blue.
Eobard would disappear again during the DC 52 reboot but as of July 2015 his making his first appearnce in the new DC 52 Reboot and thats pretty much the story behind Eobard Thawne.
There have been other Reverse Flash's Hunter Zoloman and Daniel west but thats a story for another day

Harrsion Well's and Eddie Twane never appeared in the comics he was made for the Tv show of The Flash.

Episode 21 “Grodd Lives” Official Description:

GRODD RETURNS! — Barry (Grant Gustin) must deal with the Reverse Flash’s (Tom Cavanagh) latest threat to a member of the group. To make matter worse, Dr. Wells unleashes Grodd on the city in order to distract Barry and the team. Joe (Jesse L. Martin), Barry and Cisco (Carlos Valdes) head down into the sewers to catch Grodd but the gorilla quickly gets the upper hand after he kidnaps Joe. Iris (Candice Patton) and Barry have a heart to heart talk.

The Reverse Flash art promo

Just watched Ep 19 "Who is Harrison Wells?", all i will say is the end jaw hits ground and with a only a few Ep's left things are really kicking off.

Preview pics from Ep 21 “Grodd Lives.”

Looks like things are kicking off, oh yeah