Chernabog's minions appear to be quite evil, hostile, and mischievous for their personality. Several of them are shown taking glee in performing acts of debauchery, although it appears they are fearful of Chernabog to an extent, as the black god is not above subjecting his own followers to torment to amuse himself.
These demons come in lots of different shapes and sizes. Most of the ones seen are ethereal cloaked specters with red eyes. However, there are some who resemble witches and horsemen in skeleton form, and even varieties of skeletons, satyrs, harpies, small imps, and other animals. The horsemen have strange horses with bovine heads.
During the "Night on Bald Mountain" sequence from Fantasia, Chernabog summons numerous ghosts, demons, and monsters from the graveyard of the village which Bald Mountain overlooks. They seemingly represent the pagan religions interpreting them as evil. Being summoned by him, they transformed into animals for Chernabog's delight as he throws them into the fire. With his own powers, he reveals that they are as disposable as they look, burning them in his own hellish flames. They, like Chernabog, are vanquished when the morning arrives.
The scene from "Night on Bald Mountain" is represented as Chernabog sends his army of demons to ruin Mickey Mouse's imagination under the orders of the Evil Queen. We see the face of a skull, a witch, and many other phantoms. They were destroyed in the final battle between Maleficent and Mickey Mouse, restoring the powers of Light.
One of the phantoms riding a demonic horse makes a cameo appearance as the Horned King in one of Hen Wen's visions. Other of the minions, famous for switch his color white to black two times and return to white is very similar to Horned King in a smaller size, Chernabog and his minions must have been a reference for the animation of Horned King.
All the "species" of minions appear to represent something considered bad or sin in the Christian religion. The witches and demonic horsemen are an allusion to the holy inquisition. The harpies and satyrs represent the paganism, the skeletons can be a metaphor for the "dark age" because skeletons were used by the scientists of the time for studying the nature and the human anatomy. Chernabog represents Satan running the bald mountain (hell) with his imp minions and punishing the ghosts for their sins (as is believed in the Christian religion).
In "Fantasmic!" the songs have been remastered (not just Chernabog's theme but "Pink Elephants on Parade","Poor Unfortunate Souls" and the instrumental played when Evil Queen transforms) and the minions earned phantasmagoric sounds like screams and cries.
The ghosts come from their graves in a cemetery, but some come from gibbets. Leaving implicit that they disobeyed a law in life.
Some of Chernabog's minions (the witches, ghosts, skeletons, and henchmen) return to their graves and reform when the light refuses Chernabog, but they possibly were called in for another Walpurgisnacht.
In Once Upon a Time, Chernabog's minions don't appear. However, the Wraith had a similar appearance to the ghostly minions with red eyes and cloak.