The Fountainhead
Ellsworth Toohey is the antagonist (or the bad guy) of the story.  He tries to stop Roark from being successful by controlling people who are weaker or timid. He believes in collectivism (when people join a group and they lose their own identity). He only helps people who he thinks are not very smart and not very talented. Dominique believes he is trying to control the Wynand newspapers.