The Flash
Zoom (Tony Todd) makes his debut in episode 6 of "The Flash" Season 2. The CW

Throughout five episodes of "The Flash" Season 2, all fans have been hearing about is Zoom (Tony Todd). The villain has left a pretty big impression on Barry's (Grant Gustin) new Earth 2 friends, and every metahuman the Flash has faced this year has been sent by Zoom to kill him. Now, thanks to promotional photographs (shown above and below) of episode 6, "Enter Zoom," viewers can actually see what all the fuss is about -- to be fair, the character has made a few cameo appearances this season already, but now fans can really size up the usually-supersonically vibrating speedster before he and Barry get down to business.

The photos of the masked foe raise one very important question: Who is Zoom? Tony Todd has been the man behind the digitally altered voice of the bad guy, but who is hiding beneath the mask? Earth 2 and the multiverse allow for a crazy number of wacky possibilities, so the Internet has been getting crowded with theories -- Reddit users even began spreading a theory that Zoom is Patty Spivot (Shantel VanSanten) as a sarcastic response to all the speculation.

The Flash
Zoom (Tony Todd, left) pins Barry Allen (Grant Gustin) in episode 6 of Season 2 of "The Flash." The CW

Here are four possibilities about Zoom's true secret identity:

1. Barry Allen 2

Maybe the only speedster in the universe faster than Barry is, well, Barry! Harrison Wells (Tom Cavanagh) has already proven that characters' Earth 2 versions can have drastically different personalities. Could Barry's Earth 2 self be an evil villain determined to be the only speedster? Barry started this season attempting to push away those who were close to him out of fear of putting them in danger. Perhaps Zoom is a peek into what the world would look like if the Flash did not have that kind of support system. It would also make sense for Earth 2 Barry to have some beef with Earth 2 Dr. Wells. In any case, the potential for a very different Barry has been foreshadowed by the CW series all season.

2. Henry Allen 2

One of the most popular theories on Reddit is that Zoom will turn out to be none other than the Earth 2 version of Barry's own father Henry (John Wesley Shipp). There has not been much evidence to indicate this is the case -- although some fans have tried to point to similarities between the jaw lines of Henry and Zoom in the promo photos -- but, thematically, it would check out with what the show has done this season. Barry freed his dad from prison at the beginning of Season 2 only to watch him leave town. Henry has been missing in action since, so it would be fitting that the next time Barry sees his father, it is as his archenemy. Plus, fans of the 1990s incarnation of "The Flash" on television would welcome the chance to see Shipp in costume again, even if it was one of a different color.

3. Eddie Thawne

This is another far-fetched, but popular, theory on Reddit. Eddie (Rick Cosnett) was killed in the Season 1 finale, but maybe he landed in Earth 2 after being sucked into the singularity just in time to become Zoom and wage war against all speedsters. The character has not appeared in the series since Season 1, and Cosnett has not seemed to be a part of the Season 2 cast, but "The Flash" producers have promised they are playing a long game with the Zoom reveal. Perhaps by the time the villain gets unmasked, Eddie and Cosnett will have returned.

4. Eobard Thawne

At last, we arrive again at the curious case of Eobard Thawne (Matt Letscher). The archvillain Thawne, who as his real self was played by Letscher in a Season 1 flashback episode, was killed in the Season 1 finale when Eddie shot himself, thereby erasing Thawne's existence (Eddie was a forebear of the from-the-future bad guy). However, there could be an Eobard Thawne in Earth 2 as well! That Thawne may or may not have taken control of Dr. Wells 2's body and may or may not be currently hanging out in STAR Labs with Barry. That appears unlikely, though, because episode 5 revealed that Zoom kidnapped Wells 2's daughter Jesse (Violett Beane), so why would Zoom kidnap his own daughter? It is also possible that a non-Wells-inhabiting Eobard Thawne 2 became Zoom. Barry has never seen Thawne as his Letscher-portrayed true self, so that unmasking would be a bit anticlimactic for the show's hero, but it would be a trippy twist for fans.

"The Flash" airs on the CW Tuesdays at 8 p.m. EST. Watch the promo for Season 2, episode 6 below: