Reverse-Flash, a.k.a. Professor Zoom, has a long comic book history of screwing up Barry Allen's world. He's the antithesis of the Flash in more ways than one, and it makes him the perfect villain for Allen to clash with time and time again.
Judging from leaked set photos, it looks like The Flash television show is wasting little time in introducing the character. The images below were taken from The Flash set in Canada, where the show is currently filming its mid-season finale. You can check out more photos here.
From the looks of things, Barry appears to be outmatched, with Reverse-Flash beating Barry down before doing some touchdown celebrations while standing Allen's defeated body. Costume-wise the character looks nearly identical to the Flash in all but color, with the arms and pants going from black to yellow.
Another look at Reverse-Flash can be seen in a tweet, since deleted, thanking the cast and crew of the show.
Interestingly enough, it looks like Professor Zoom actually already appeared in the show. If you blinked you might have missed it: he is the yellow blur that Barry sees when his mother is murdered, or "the man in the lightening."
It looks like The Flash will be following the comic book version of Reverse-Flash very closely. In the comics, Reverse-Flash travels back in time to ruin Allen's life on a regular basis. While several characters have been Reverse-Flash, the most well known version of the character is Eobard Thawne, who later goes on to also murder Allen's wife Iris.
There is already an Eobard Thawne on the show; he works as a police detective alongside Allen's surrogate father, Joe West. Whether or not Thawne turns out to be Reverse-Flash or not, chances are looking good the character traveled in time to plant himself in Barry's life. Thawne is also partly responsible for the DC Comics New 52 reboot event Flashpoint, which had Allen completely resetting the DC Comics universe after finding himself in an alternate timeline.
Be sure to read up on our list of some of the greatest Flash stories ever told. With Reverse-Flash confirmed, it is only a matter of time before the show begins adapting some of the character's most iconic comic storylines.
