|“||Boxman, my boy, your superpower must be failure. Heh. It's the only thing you're good at. We don't approve of you, darling!||„|
|~ Milliam mocking Boxman.|
He is voiced by Justin McElroy.
Stop Attacking the Plaza
Milliam attends a meeting with Boxmore's other top investors, Cosma and Vormulax, to discuss the company's production sale. When Boxman attempts to sneak out of the meeting to attack the Plaza, the investors, specifically Cosma, call him out for constantly abandoning his job to attack the Plaza and challenge him not to attack it for 24 hours, otherwise they will pull all funding from him. Milliam and the others leave afterwards.
Villain's Night Out
Milliam hosts a Villain Party for various other villains on his yacht, seemingly inviting every villain except Boxman, who ends up weaseling his way in by convincing Professor Venomous to take him as his plus one. At the party, Milliam greets the arriving guests, but is horrified when Boxman arrives, telling Venomous that he is a "joke villain". Venomous insists that Boxman forced himself along, but won't be noticed by anyone, only for he and Milliam to be further horrified when Boxman begins gobbling up the food at the snack table.
Milliam calls for all the other villains attention and thanks them for their attendance, promising them a memorable party and handing out complimentary T-Shirts. When Boxman begins making a mockery of himself and the other villains on the dance floor, a distressed Milliam claims that he is ruining everything, forcing Venomous to step in to try and talk Boxman down, to no avail. After karaoke (which Boxman also ruins), Milliam states that it is time for the villains' Explode-Off contest, in which each villain launches several missiles to see who can make the best explosion. On Boxman's turn, he launches numerous missiles at a location without them blowing up, and Milliam remarks that his attempt wasn't too bad, only for one of his minions to show him where the missiles had been launched. A panicked Milliam informs the other villains that Boxman had shot the missiles at P.O.I.N.T. headquarters (in an attempt to impress Venomous), causing everyone to panic. Although seemingly having no effect at first, the missiles trigger P.O.I.N.T.'s defense system, which destroys the majority of Milliam's yacht. Milliam tells his guests not to worry, having prepared several of his minions to swim them to safety in such an event. Milliam confronts Boxman and tells him that his only superpower must be failure, before literally walking over him and floating away, stating that he and the other villains do not approve of him.
Villain's Night In
Milliam is a thoroughly smug, arrogant, sophisticated, and snobbish person. He voices his opinions without regard of who may be hurt by them, specifically Lord Boxman, whom he regards as a joke villain incapable of doing evil. Although he is very condescending and disdainful towards Boxman, he is friendly and inviting towards the other villains, and seems to enjoy their company. He can also be very egotistical and pompous, handing out complimentary shirts of depicting himself to everyone (despite the fact that most didn't actually want one).
- Billiam Milliam was the only of the three Boxmore investors in "Stop Attacking the Plaza" that had not been named/introduced prior to the episode or during the episode, leaving his identity a mystery up until "Villain's Night Out".
- Justin McElroy's performance as Milliam seemingly takes inspiration from his character Taako in The Adventure Zone.