At least five of the Flash's most famous enemies have appeared on the CW in season one and that makes me think they're building up to something huge

The first season of the Flash is putting together the enemies of the fastest comic book superhero in the universe, and they're collectively known as the "Rogues." So far, this is what we've seen:
Captain Cold, a.k.a., Leonard Snart. Played by actor Wentworth Miller in the television show, Snart stole a weapon from S.T.A.R. Labs that fires out a beam of intense cold that Cisco Ramon created as a "solution" to "The Flash" should he prove to be evil . Basically, this gun has the ability to freeze anything to absolute zero. He's the leader of the "Rogues" since he is charismatic, and Snart has what I would call a "Jim Jones" kind of persona, able to make emotional appeals to naturally occurring megalomania (in his teammates) through grandiose promises of rulership. He first appears in the episode "Going Rogue," which is number four in season one.
The Pied Piper, a.k.a., Hartley Rathaway. Played by actor Andy Mientus, Hartley has created a pair of gloves that allow him to manipulate sound waves. He's a former protégée of Dr. Harrison Wells and is after vengeance because Wells fired him, threatened him, and ignored what he had to say about the dangerous particle accelerator. Hartley, much like Captain Cold, is not a meta-human. He's just really really smart, and he basically has gone evil because he's filled with so much hatred for Wells, Cisco, Snow, and Barry Allen. Hartley is introduced in the episode "The Sound and the Fury" which is number eleven in season one.
Weather Wizard, a.k.a., Clyde Mardon. Played by Chad Rook, Clyde robbed a bank with his brother Mark (who's the Weather Wizard in the comic books). Clyde is a meta-human, having derived his powers from being in a plane that exploded when the S.T.A.R. Labs particle accelerator went boom. As far as I know, this character died in the Pilot episode of season 1. It's still interesting they introduced him though. Maybe they have plans for a resurrection.
Heat Wave, a.k.a., Mick Rory. Played by actor Dominic Purcell, Heat Wave makes his appearance in the tenth episode entitled "Revenge of the Rogues." Heat Wave's character is a friend of Captain Cold's, and he has basically the opposite fetish of Cold in that he's a pyromaniac. Cold gives him a gun that's essentially a bottomless flame thrower so that they can put the squeeze on Barry by hitting him simultaneously with both fire and ice.
Captain Boomerang, a.k.a., Digger Harkness. Played by actor Nick Tarabay, Boomerang was in the crossover two-part episodes "Flash versus Arrow" and "The Brave and the Bold." In the episodes, Harkness is a guy that kills people with deadly metal boomerangs, and who has a connection with A.R.G.U.S., which may or may not have something to do with the Suicide Squad. I wish there was more information available to us fans.

That's five out of (I believe) what might be ten of the "Rogues." I think at this point I'm most interested in seeing them break out Gorilla Grodd (there's going to have to be some serious CGI for this one), and then more on Professor Zoom (which we now know for certainty is Dr. Wells AS I had predicted last year).

Please stop by Friday when I post my interview of Woven authors Michael Jensen and David Powers King. I'm going to their book signing here in Salt Lake City at The King's English. I shall take a few pics and post them for you :).