"The Flash" Season 4 is breaking with tradition by casting a main villain who is not a speedster. Speculations suggest that Team Flash will face the most diverse set of villains yet with the entry of The Elongated Man, The Thinker, and The Mechanic. Also, there is the unresolved story arc of Caitlin Snow.

No speedster main villain in 'The Flash' Season 4

Following three consecutive seasons of having Speedsters as the main antagonist, Team Flash is reportedly going to tangle against its greatest challenge to date.

Andrew Kreisberg, speaking at Paley Fest in Los Angeles, confirms that "The Flash" Season 4 is "not going to have a speedster as the main bad guy."

However, it does not mean that an evil speedster is not going to make an appearance. The show has a great history in keeping story arc information close to their vests that fans can rest assured that they will be in for a treat in the upcoming season of the "The Flash."

While it may be true that speedsters are the most dangerous beings in the DC Universe, having a non-speedster antagonist would not only be refreshing for fans, but it actually makes sense for series "The Flash." After tangling with The Reverse Flash ("The Flash" Season 1), Zoom ("The Flash" Season 2) and the God of Speed Savitar ("The Flash" Season 3), Team Flash now has considerable experience in taking down speedsters.

What happens to Killer Frost?

In "The Flash" Season 4, the fan favorite Caitlin Snow, also known as Killer Frost, emerged a changed a person. Caitlin herself that she is something else, not really the Caitlin and Killer Frost, that Team Flash know. Integrating these two separate personalities inside her head would take its toll on anyone.

But for someone like Caitlin Snow who has tremendous super powers, there will always be that pull to dominate. That being said, the original Caitlin can offer some semblance of restraint as she is naturally a good person. It will be critical for Team Flash that Caitlin returns back in the fold having full control of her abilities in "The Flash" Season 4 as they are going to be challenged like never before with the appearance of new super villains.

Three new super villains: The Elongated Man, The Thinker, The Mechanic

"The Flash" Season 4 casting descriptions last week and it offered fans a glimpse of the future. Actually, one of them has been mentioned a few times in the Season 3. Season 3 main antagonist Savitar and guest villain Abra Kadabra, both of whom are revealed to be from the future, revealed one name that will have a huge impact on Barry Allen's life: Devoe.

Clifford Devoe, also known as The Thinker, is a staple in "The Flash" comic book series. Devoe is a former district attorney with incredible IQ who was transformed by the particle accelerator explosion and became a meta-human. The Thinker is reportedly going to be a regular on "The Flash" this season in which fans will see momentous battles between the "fastest mind alive" against the "fastest mind alive."

The Thinker will team up with a new character called The Mechanic.

Not much is known about this female character and there seems to be no counterpart for her in "The Flash" comics. The casting description for "The Flash" Season 4, however, suggests that the mechanic is a talented engineer who provides The Thinker with devices and tools for his projects. The Mechanic is reportedly going to be a major recurring guest star in season 4.

Ralph Dibny, also known as The Elongated Man, will get fans excited because of his comic book origins. The casting description of The Elongated Man reveals that he is a meta-human "who can stretch his body to superhuman length and sizes." The Elongated Man will join Team Flash and is described as a major recurring guest star with an option to be a series regular for "The Flash" Season 5.

'The Flash' Season 4 air date

Fans of the Scarlet Speedster wouldn't have to wait long to find out what really happened to Caitlin Snow, or whether the Elongated Man would turn out to be a permanent ally of Team Flash. "The Flash" Season 4 is slated to premiere on October 10, 2017.