Cartoon Network released a new show that would end up becoming one of the most beloved Cartoon Network shows of the 2000s: Ben 10. It would go on to have four seasons before returning in the sequel shows Ben 10: Alien Force, Ben 10: Ultimate Alien, and Ben 10: Omniverse. Then, in 2016, Ben 10 would be rebooted with a more comedic angle.

RELATED: 10 Best Superhero Movies & TV Shows That Aren’t Based On Comics

The story of a young boy who ends up with an alien watch that can transform him into different extraterrestrials has become a classic superhero animated series, and it features a slew of many great episodes to watch.

Kevin 11 - Season 1, Episode 7 (8.6)

Ben and Kevin talking in an alley in Ben 10.

The first season of Ben 10 introduces Kevin Levin, a boy with the ability to absorb any energy and use it as a weapon. Kevin Levin and Ben Tennyson hit it off, but, of course, Kevin turns out to be malicious and wants to use the Omnitrix to commit crimes and make himself more powerful.

Kevin would go on to become a recurring villain in the original series before becoming a hero in the sequels. Kevin was a dark character and effective villain, but he showed moments of heroism, which helped to set up a redemption later on in the show.

Ghostfreaked Out - Season 2, Episode 11 (8.6)

Ghostfreak separated from Ben in Ben 10.

One of the original ten aliens in Ben's loadout, Ghostfreak, is acting strange. Ben is no longer in control, and, instead, Ghostfreak becomes sentient and separates from the Omnitrix to carry out his own plot to take over the world.

This episode was praised for its unique concept and evolving Ghostfreak into a terrifying recurring threat for the series. The show was never afraid of showing the darker side of alien threats, and this one is a perfect example of that.

Ken 10 - Season 4, Episode 7 (8.6)

Ben giving his son Ken his own Omnitrix in Ben 10

A glimpse into Ben Tennyson's future in a world where he has thousands of aliens on his Omnitrix which he can transform into. He's now the intergalactic superhero known as Ben 10,000, but he's also a single father trying to raise his son Ken. Ken is given his own Omnitrix and the ability to transform into aliens.

The episode focuses mainly on Ken as he learns the ropes from his father while trying to learn of the responsibilities that come with the Omnitrix. The cyberpunk future and some twists and turns led to the episode becoming a fan favorite.

Framed - Season 2, Episode 3 (8.7)

Newspaper showing Ripjaws robbing a bank in Ben 10.

Crimes are being committed all over the country by Ben's different alien forms. So, Ben, Gwen, and Grandpa Max immediately begin to investigate and find a culprit responsible or if the Omnitrix is acting up. It leads to an interesting confrontation that should not be spoiled.

RELATED: 10 Best Cartoon Shows That Are Written For Both Kids & Adults

Another one of Ben 10's strengths is that different episodes play off of different genres. This is similar to Marvel Cinematic Universe movies with Ant-Man as a heist film or Captain America: The Winter Soldier as an espionage/conspiracy thriller. This episode more embraces an investigation thriller with some action sequences.

Benwolf - Season 3, Episode 5 (8.7)

Ben slowly transforming into Blitzwolfer in Ben 10

Returning to horror, Ben is bitten by an alien werewolf trying to protect Native-American land. Unfortunately, the bite reacts poorly with the Omnitrix. As a result, Ben slowly begins to transform into a werewolf, which is a bit different from most werewolf transformations seen in films.

Rather than a single, painful transformation, Ben is mutating in a slow process, providing a bit of body horror similar to David Cronenberg's The Fly, albeit less graphic and disturbing. Ben's new wolf form known as Blitzwolfer would end up becoming a favorite that fans wished would have appeared more often.

Be Afraid Of The Dark - Season 3, Episode 12 (8.7)

Snare-Oh unleashing his power in Ben 10.

Harkening back to the classic Universal monsters of the 1930s, the episode "Be Afraid Of The Dark" features the return of Ghostfreak as he has assembled a team of a Frankenstein-like monster, a mummy-like alien, and the werewolf from the "Benwolf" episode.

This episode is the continuation of "The Return," allowing for the monstrous villains to continue to shine. With a nice blend of darkness and a clear love for the classic monsters, it's easy to see why this episode is loved. The two-parter would also be the end of an era as it is Ghostfreak's final appearance in the series.

Ben 10,000 - Season 3, Episode 1 (8.8)

Ben saying goodbye to his future self in Ben 10.

The first time fans saw the future version of Ben was in the episode which takes a different approach to time travel. Ben is taken to the future to meet his future self who has become a self-centered, mean-spirited man with no time for his family or friends.

RELATED: 10 Best Movies & Shows About Time Travel, Ranked

This episode is why fans were excited to see Ben 10,000 return in the final season. Not only is the future world visually stunning, but seeing a young Ben and older Ben both learn valuable lessons brings a lot of heart to the episode. It's a similar dynamic seen in the big crossover episodes of Doctor Who.

Secrets - Season 1, Episode 13 (8.9)

Vilgax interrogating Ben Tennyson in Ben 10.

After several episodes of build-up, the villain Vilgax himself comes after Ben in order to get the Omnitrix. Voiced by Steve Blum, who has voiced thousands of characters including Sub-Zero from Mortal Kombat, Vilgax proved to be the ultimate and iconic villain of Ben 10 with this episode.

This is where the show started showing more grit and became more of a sci-fi epic, showcasing Grandpa Max's past, a threatening villain, and a lot of well-executed action. It showed that Ben 10 could be a monster-of-the-week type of show while still having an evolving story throughout.

Back With A Vengeance - Season 2, Episode 13 (9.1)

Ben giving up the Omnitrix to Vilgax and Kevin in Ben 10

Two of Ben's most famous foes, Vilgax and Kevin, team up to try and kill Ben while gaining the power of the Omnitrix. Obviously, the fans loved seeing the two villains fail to get along, but this episode gave a first glimpse at the Omnitrix at full power by giving Ben the ability to change into any alien at will. This ability may be short-lived, but it showed Ben's potential which would be fully realized with Ben 10,000.

Secret Of The Omnitrix - Season 4, Episodes 1 (9.3)

Ben, Tetrax, Myaxx, and Azmuth encountering Vilgax in Ben 10 Secret Of The Omnitrix

In many ways, Secret Of The Omnitrix is the penultimate episode of the first series. It features Vilgax returning yet again as Ben and his old ally Tetrax are on the journey to find the creator of the Omnitrix: Azmuth. This 90-minute special was the Ben 10 movie that had the fanbase cheering.

It mixes blends sci-fi action, an intergalactic journey, throws in some twists, and further develops Ben as the true hero of the galaxy. Tara Strong has always given a strong performance as Ben, but this was easily the best she had ever done as the character.

NEXT: Tara Strong's 10 Best Performances As DC's Harley Quinn