The Flash is turning out to be one of the best comic book shows that any of us have ever seen. Between the emotional story arcs, compelling fight scenes and quirky humor, The Flash has it all. Among its many standout characters, this CW show does a great job of portraying its villains. From Reverse Flash to Gorilla Grodd, the show features many great interpretations of classic comic book characters.

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Having just finished its fifth season, the question remains: what villains are there left? Although Flash has one of the best rogue galleries of any comic book superhero, after five seasons most of these rogues have already made their on-screen debut. For any fans wondering who's left, here are the top ten Flash villains we have yet to see on the show.

10 The Changeling

Erik Razar was a low-life criminal who attempted to escape prison. On his way out, he accidentally received a powerful jolt of electricity, giving him the power to shapeshift into animals.

A great idea for a single episode, the story of Changeling would be an interesting one and he would be a fun character to team up with the other rogues. The show could either show his abilities as light-hearted in nature or super scary, based on the animals he transforms into.

9 Steve Palmer

While not quite as imposing as the other villains on this list, Steve Palmer would make for a great addition to the show. In the comics, Barry Allen's Flash became so popular that Hollywood decided to make a film about him. The lead actor cast in the role of the scarlet speedster was the handsome Steve Palmer.

Utterly falling in love with the fantasy of being the Flash, Steve manages to catch Barry and tie him up in his trailer. Thankfully, Iris shows up to save the day and free Barry. While not material for a season-arcing big bad, Steve Palmer would make for a great villain in a comical one-off episode.

8 Mazdan

A thief from very far in the future, Mazdan was sentenced to the endless desolations of the 50th Century. However, when his accusers sent him off in a time capsule, it malfunctioned, instead sending him to Barry Allen's time.

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With all the time travel elements The Flash has become famous for, Mazdan would fit right in. His futuristic weapons and advanced knowledge would make him a great villain. Also, Mazdan seems to be from much further in the future than any of the show's characters so far, leading to some interesting ideas the show runners could play around with.

7 Manfred Mota

Going by three different aliases, Mota has fought many Flashes over the course of his comic book career. Going by Atom Smasher (not the one we've seen), Professor Fallout, and lastly Fusionn, this character has fought Barry, Wally, Jay and even Bart Allen.

Imbued with the power of a nuclear power plant, Manfred Mota would make for an powerful enemy. His daughter in the comics also dated Bart Allen, Barry's descendant from the future. Although we are unlikely to see another Flash descendant in Season 6, Mota's daughter could still be an emotional character that adds to the drama of the show.

6 Turbine

A former airman, Roscoe Hynes was in charge of a fleet of war planes. After breaking from his unit for no apparent reason, Roscoe and his plane disappeared with no explanation.

As it turns out, Roscoe was stuck in the Speed Force. He remained within it for 70 years. During an adventure where Flash entered the Speed Force, Roscoe saw his opportunity and made an escape. Unlike most characters who tapped into the Speed Force, Hynes doesn't have super speed. Rather, he can merely spin his body at high speeds like a top, creating vortexes and leaving devastation in his wake.

5 Mob Rule

Although mentioned briefly, Mob Rule has yet to show up in an episode of The Flash. Manuel Lago was an old friend of Barry Allen. After being experimented on by the CIA, Lago learned of his abilities during a brutal interrogation conducted by a criminal organization.

When losing a limb, not only could Manuel regrow his own, but the lost limb would also regrow and form a new Manuel. This ability to duplicate is very powerful and counters Barry's speed nicely. Danton Black, an enemy from Season One, also had this power. The final fight between Barry and Black was one of the most exciting of Season One. Fight scenes with Mob Rule would be even better.

4 Captain Boomerang

Although the Digger Harkness version of the character has already appeared (and died) on Arrow, Owen Mercer's Captain Boomerang has yet to appear on the show. A classic member of the Rogues, Captain Boomerang is a must have for a Flash TV show, and they need to find a way to introduce this villain sooner rather than later.

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The abandoned son of the first Captain Boomerang, Harkness, Owen Mercer reconnected with his father and took up the mantle after Digger's passing. He served as a member of the Rogues, and caused many problems for Barry Allen over the course of his criminal career. We hope to see him soon.

3 Star Sapphire

DC Comics Star Sapphire

Star Sapphire is typically a Green Lantern villain. What many comic book fans may not know is that the original Star Sapphire was an enemy of Jay Garrick's Flash. Traveling to Earth from the 7th dimension, this character claimed to be a queen hellbent on destroying all plant life, depriving the planet of all its oxygen.

Whether they choose this original Star Sapphire or the more well-known Carol Ferris, Star Sapphire would make for a big introduction that would turn many comic fans' heads. Not only is she very powerful, she has an interesting history and  fits in perfectly with the tone of the show.

2 Cobalt Blue

In order to cover up the fact that he had accidentally killed a child, a doctor separated Barry Allen and his twin during childbirth and told the Allen's that their second child was stillborn. The family whose child was killed and replaced with an Allen? The Thawnes.

Later named Malcolm Thawne, this brother of Barry Allen would go on to become the villain known as Cobalt Blue. With the ability to absorb Flash's speed and use it to generate blue flames, this baddie has all the makings of a season-arcing main antagonist.

1 Inertia

Inertia would be a wildly compelling villain to fight alongside Barry's arch-nemesis. The clone of Barry's ancestor Bart Allen, it was later revealed that the two of them were also half Thawne. Both twists would make for great drama, and feel like something a show like The Flash would do in its 6th or 7th season.

While Bart Allen has not yet appeared on the show, Nora Allen has. Perhaps the TV version of Inertia could be a clone of Nora. Created by the Reverse Flash and preserved in the Negative Speed Force, this clone could become the apprentice of Flash's greatest foe and haunt the speedster for years to come. Let's hope that's where things are headed.

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