Zs'Skayr's Minions

Ghostfreaks minions are people or Ectonourites who work for Zs'Skayr

Frightwig
Frightwig has pale skin, a tight-fitting body suit, and five orange tentacles for hair. The tentacles are extremely powerful, giving her strength equal to that of Thumbskull. They are also tipped with metal orbs for greater concussive damage. She's also extremely nimble and skilled in acrobatics. However, she, like Acid Breath, is always easily subdued by Ben, usually by getting tied up by her own hair. The enhanced version of "Ben 10,000" reveals that Frightwig, now middle aged, is the leader of the Nuevo Circus Freaks from 20 years in the future.

Acid Breath
Acid Breath is one of Zombozo's three minions, and without a higher rank to command them, he acts as the trio's leader (with somewhat inconclusive results). His appearance is quite like that of a zombie. He has the ability to project corrosive acid from his mouth in the form of either a vapor (hence the name "Acid Breath") or a liquid, a trick he implies was taught to him by his mother. This acid can easily dissolve whatever he wants it to, even metal and stone. Despite the potency of his breath, he is one of Ben's least dangerous foes. If his mouth is jammed by an object (such as a baseball), or if something causes him to cough and gag (such as when Gwen blew a fire extinguisher's contents into his mouth), Acid Breath will be briefly unable to use his powers and will be vulnerable to attack.

Thumbskull
Thumbskull, as the name suggests, has a head shaped like a thumb (complete with a fingernail-like hairstyle on his forehead). He also has incredible strength (though inferior to that of Fourarms), but limited intelligence. Like his co-workers, Thumbskull is always beaten very quickly by Ben, even worse than the other two. His name is a play on the insult "numbskull", as well as the obvious appearance gag.

Loboan
This alien werewolf was sent by Doctor Vicktor to steal communication equipment from a reservation that Ben, Gwen, and Grandpa Max were visiting in "Benwolf". Ben first fights against the Loboan as Wildvine. When Ben is transformed back to his normal self by the Omnitrix, the Loboan slashes the Omnitrix, causing the device to download his DNA (signified by its face turning yellow) and gradually change Ben into the form. In their second battle, the Loboan appears to be killed by a cave-in, though it is not actually shown dead. The device that it was building is shown coming online at the episode's end, its purpose left unrevealed. The Loboan is revealed to have survived in "The Return", and its device is used as part of Ghostfreak's plan to block out the sun. In the next episode "Be Afraid of the Dark", the Loboan's transmitter explodes when Grandpa Max rams a space shuttle into Ghostfreaked's corrodium projector, destroying it. It is unknown if the Loboan survived the explosion of the transmitter. Werewolf appears as an enemy in Ben 10: Protector of Earth in two variants: Fangface and Fangface Howler

Mummy (Thep Khufan)
The Mummy appeared in "Under Wraps", a Thep Khufan from the planet Anur Khufos, was sent by Doctor Vicktor to find a dangerous element called corrodium that crashed on Earth millions of years ago. Grandpa Max explains that the crystals are a potent but unstable power source, and the radiation emitted by the crystals causes almost instant mutation in humans and other Earth-born creatures. Todd Maplewood, a boy Ben and Gwen met, said it arrived in purple lightning, which is the same way the Alien Werewolf arrived in "Benwolf". Max states there may be a connection between the werewolf and mummy, which is proven in "The Return". During Ben's battle with the creature, its DNA is absorbed by the Omnitrix, giving Ben access to the form. The mummy is frozen solid by Upgrade merging with a liquid oxygen device and buried, along with its corrodium, under a thick bed of concrete. It was released by the werewolf in "The Return", and assists in Dr. Vicktor's plan to plunge the earth into eternal darkness. When Ben is fighting Ghostfreak, Doctor Vicktor, and Mummy in "Be Afraid of the Dark", Doctor Vicktor inadvertently sends both himself and mummy to an unspecified location, most likely the Null Void, through an ill-timed use of his teleportation device. Ben's version of Mummy is named Benmummy. Mummy appears as an enemy in the game "Ben 10: Protector of Earth" as two enemies: Mummy and Cyclone Mummy.

Dr. Victor (Transylian)
Dr. Victor is a Transylian from Anur Transyl (an alien resembling Frankenstein's monster) who works at NASA, disguised as a human scientist as a means to hijack a space shuttle. He is intelligent, and working for Zs'Skayr; his immediate plan was to resurrect his master, whose ultimate plan was to prevent the sun's light from reaching the earth using various satellites (therefore meaning that Zs'Skayr would be at full power all of the time). He is not treated with respect after Zs'Skayr is resurrected. After he asks why they need Ben, Zs'Skayr takes control of his body and throws him around. He serves as the unofficial leader of the three horror-themed aliens. The purple lightning that the previous two horror aliens appeared in was generated by a teleportation machine that he uses. His name is derived from the name of Victor Frankenstein from the Mary Shelley novel. His first appearance is in "The Return", where he succeeds in reviving Zs'Skayr. In the next episode "Be Afraid of the Dark", Ben fights Doctor Vicktor and Zs'Skayr on Earth. Ben accidentally gains use of Doctor Vicktor's form when Vicktor finds Ben and grabs him by the wrist, unintentionally adding his DNA to the Omnitrix. Vicktor essentially defeats himself near the end of the episode. In an attempt to teleport Ben to an unspecified location, he and the mummy alien are tossed into the portal he created. Ben 10: Protector of Earth features "Vicktors" as enemies on Zs'Skayr's planet.

Various Mutated people and animals
The Mummy can create and mutate people and animals into savage purple mutants which can be considered as his minion.

Game Appearance
In addition in the cartoon network game Cannonbolt Pinball: Ghostfreak's Revenge, it is listed that Zombozo is one of Ghostfreaks minions but this is false, because Zombozo was destroyed before Ghostfreak's appearance, though it is possible its refering to Ghostfreak's DNA doner, though this seems unlikely as Zombozo was literally scared to death by Ghostfreak's true appearence. The game may be considered non-canon.