Aloysius (Shempy) O'Hare (Usually just called O'Hare) is The Mayor of Thneedville, who is also the Once-ler's successor of business. As early as late teenhood (when he still had braces), he got ideas for making money when he saw one of the billboard workers coughing on smog while wondering who will make "the next best thing" after the thneed factory had to shut down for good. Years passed, and O'Hare made a fortune selling oxygen tanks for a machine he designed to keep the otherwise-smoggy-air fresh for Thneedville residents, but in order to sell what people used to get for free, O'Hare's air company went great lengths to keep the locals from leaving town, thus finding out the alternative to his methods is replanting the trees. Because of that, Ted Wiggins made an enemy out of this so-called "elected hero" when the teen boy tried to get a real tree for the girl of his dreams. When Ted spoke for the trees (as though a part of the Lorax was within him) by tearing down the walls of the town to reveal the truth and showing the last tree seed as a start of many much-needed changes for the all-artificial town of Thneedville, O'Hare tried in vain to get the citizens on his own side, revealing his true nature in the process by threatening to fire his delivery man Sai and singing that the seed should die. Through this, the residents of Thneeville saw O'Hare as the greedy dirtbag he really is, and they impeached him by having him blasted off in a jet-helmet.
- His last name might be a reference to Fred O'Hare from Universal Studios' other film, Hop.
- His full name is Aloysius O'Hare, according to the Thneedville Song.
- He is voiced by Rob Riggle.
- He bears some striking resemblances to Lord Farquaad from Shrek.