Aloysius O'Hare (voiced by Rob Riggle) is the main antagonist of The Lorax. He is the greedy mayor of Thneedville and the founder of O'Hare Air, a company for bottled air. He had the city walled off to hide the environmental destruction outside.
When he was young, he worked as a janitor and had glasses and braces. He saw a Thneed billboard and was inspired to start a buisness. He had oxygen bottled and sold. He became the elected hero of the city and also their mayor. He had bees, flowers, grass, and trees manifactured so that no real oxygen would be made. But when Ted leaves Thneedville to speak to the Once-ler, he considers it a huge threat and tries to keep trees from being well known by sealing the door Ted uses to leave town, ruining Audrey's nature paintings, and even pillaging Ted's room for the seed. After a chase throughout the city, he rallies the citizens up against Ted, Audrey, and Grammy Norma, only for Ted to ram an earthmover through the wall, and O'Hare can only reveal his greedy nature to take control of his city once again. The delivery guy, Cy, who he threatens to fire, calls him a "greedy dirtbag" before he is removed from Thneedville via a rocket helmet by Morty and McGurk.
O'Hare has short black hair and is rather short himself, although he is idolized by the citizens ("Oh look, it's Aloysius O'Hare!", "The man who found a way to sell air."). He is a tycoon and wears a grey suit and black shoes
- O'Hare might be a reference to Fred O'Hare from another Illumination Entertainment movie, Hop.