Monster Masters

Monster Masters are villains (whether they are human-like, monstrous, or supernatural) who might or can command creatures and monsters of different sizes or powers, such as kaiju, dragons or others, but they are linked by having command over all kinds of monsters and creatures to do their bidding. 

Monster Masters are different from Summoners in a state of constant command. That is to say, if someone calls forth monsters from a different place or dimension, they are a summoner; if they have an army of monsters with them they are a Monster Master. Although sometimes they can be both.

The examples of a Monster Master include King Dedede (who sends monsters to attack Kirby), Red Death (who has control over thousands of dragons), Shockwave (who has control over the Driller), Malgolsha (who has the Great Hog as her right-hand beast), Lex Luthor (who owns a pet kaiju), William & Michael Afton (who had control over their animatronics; for William, the original, and for Michael, the Toys; only for the original to turn against William after they found out the truth about his colors, and the Toys were destroyed by the originals), and Godzilla (who is the King of Monsters and has innumerable authority and command over many kaiju and monsters, befitting his title).

They are the polar opposite of Monster Slayers.