Scarlet Beetle

Scarlet Beetle started as an ordinary beetle, who was mutated by radiation from an atomic experiment. With super intelligence, the ability to command insects, and proportional superhuman strength, his villain skill set is a close match to Ant-Man's abilities.  While a only slightly larger-sized insect may seem like an odd choice for a villain, Marvel's gotten away with crazier things in the past - like basically everything in Guardian's of the Galaxy. In the comics, Scarlet Beetle captures Ant-Man's technology, grows to human-size, and briefly takes over the city of New York. If done right, a human-sized beetle controlling the bugs of New York could be absolutely terrifying.

Whirlwind (David Cannon)

Whirlwind is a professional criminal and mutant with the ability to spin his body like a top (he originally called himself Human Top) at super speeds. During his villainous rein, Whirlwind served mainly as a nemesis to Hank Pym, generally as Giant Man, and Janet Van Dyne's Wasp, so an introduction to Whirlwind could give Lang's Ant-Man an excuse to explore more of the Pym Particles and develop into Giant Man. Whirlwind even becomes obsessed with Wasp, becoming her chauffeur just to get close enough to kill her. The personal vendetta and insidious behavior would make Whirlwind a perfect on-screen villain. Plus, the spinning special effects have the potential to look amazing on-screen.

Radioactive Man (Chen Lu)

Dr. Chen Lu was a nuclear physicist for the People's Republic of China researching how nuclear radioactivity could be used to make superhumans prior to exposing himself to scary amount of the material. In addition to turning him a nice shade of jade, the radiation gives him super strength, invulnerability, and the power to manipulate and absorb energy. In the comics, he goes up against Hank Pym as part of the new Masters of Evil and is ultimately defeated when Pym dampens his radiation. Though not known for battling Scott Lang, Radioactive man, especially if accompanied by more villains from the new Masters of Evil, could be a visually stunning villain to watch.

Psycho-Man

This one is ittedly a bit of a stretch, since Psycho-Man is mainly a Fantastic Four villain, and could be owned by Fox. In the comics, Psycho-Man is a the technocratic dictator of a system of worlds within the Microverse; when his realm gets a bit crowded, Psycho-Man decides that the Macroverse should be his next conquer. With his advanced technology (including a device that manipulates foes' emotions), as well as his microscopic size, Psycho-Man is pretty much the nightmare Hank Pym (Michael Douglas) wanted to avoid in Ant-Man. Though a primary foe of the F4, fans can probably see how the concept of a Microscopic universe populated with intelligent life (and a dictator needing to be toppled) would be better suited for the Ant-Man sequel.

Madame Macabre

Another villain who mainly fights against Hank Pym's Giant Man and Wasp in the comics, Madame Macabre would make a good foe for Lang's Ant-Man, thanks to her ability to change the size of objects created from a certain type of plastic. But more importantly, Madame Macabre would easily fit into the existing Marvel Cinematic Universe thanks to a connection with Iron Man 3's Mandarin. When she was a child, Mandarin saved her from being run over by a rickshaw. He ed her education and turned her into a loyal follower. While she doesn't have any superhuman abilities, her connection to the larger universe would make her a neat onscreen foe for fans.

Black Ant (Eric O'Grady LMD)

Eric O'Grady was a S.H.I.E.L.D. agent tasked with watching Hank Pym's tech. After a group of Hydra superhumans attacked the Helicarrier he worked on, he ended up gaining control over the suit, which he used to help the Avengers on several occasions and even died nobly to save the life of a child. In the comics, his death is short-lived, as a Descendant used him as a life model decoy called the Black Ant and sent him to infiltrate the team. He was able to gain their trust once again, with only Black Widow believing he was a robot. In the movies, O'Grady could start out as the Black Ant, or the second film could set up O'Grady's transition to the Black Ant.

Crossfire (William Cross)

Crossfire seems like he could be the most obvious candidate for an Ant-Man 2 villain, based solely on the fact that he is the cousin of Darren Cross - the first Ant-Man's antagonist. In the comics, he is mainly a Hawkeye foe, but his loose connection to the first Ant-Man could convince Marvel to transition him over to Ant-Man or perhaps give us an Ant-Man/Hawkeye team-up. A mercenary with cybernetic implants, Crossfire is known for stealing tech, including some of Pym's, for hire. A television version of Crossfire also has a criminal history with Lang that could play into a later story line.

Voice (Jason Cragg)

As a radio DJ with the power to make anyone do anything he commands, Jason Cragg could be a formidable opponent for Earth's Tiniest Hero. Sometimes called The Man with the Voice of Doom, Cragg started to gather a following and used his powers to convince people Ant-Man was a villain. For Ant-Man 2, Voice could be updated to host a cable TV show or become a politician instead of a radio DJ. He's also been tied to the Red Skull, which would certainly fit nicely into the larger Marvel Cinematic Universe and make him even more threatening. Any villain who has the potential to take over our heroes' minds is a villain that is particularly scary to watch in action. Just imagine if Professor X was a villain.

Black Knight (Nathan Garrett)

The Black Knight may look like a medieval knight, but he's actually a medieval knight with some pretty sweet tech, which is perfect for Ant-Man to go up against onscreen. Beyond just the awesome visuals of a flying horse, the suit of armor, and a lance that shoots firebolts, Black Knight is also a founding member of the Masters of Evil, which could bring in even more heroes and villains for Ant-Man 2. Defeating Black Knight could also set up Garret's niece Dan Whitman to come in and become the good Black Knight, a character who later s the Avengers.

Taskmaster (Tony Masters)

Taskmaster is a deadly mercenary with a unique ability that allows him to imitate the physical movements of anyone he witnesses - an ability he uses to impersonate other Marvel characters and to train criminals in secret schools across the United States. In the comics, he goes up against Ant-Man several times, usually with out superheroes making an appearance. At one point, Ant-Man and Hawkeye team up to fight him at a traveling carnival. Again, who wouldn't love to see Paul Rudd and Jeremy Renner together onscreen? The film could follow the duo as they track down each of these schools and shut them down. One of the schools could even set up a future villain for Ant-Man or other Marvel characters.