The term "yesperson" refers to a person who habitually agrees with everything or someone to curry favor, often at the expense of their own beliefs, values, or opinions. Antonyms for yesperson include "naysayer," "contrarian," "doubter," "skeptic," and "opponent." These words suggest individuals who are not afraid to express disagreement or offer criticism, and who are willing to challenge the status quo. A naysayer, for instance, is someone who habitually opposes ideas, proposals, or suggestions, especially without adequate or convincing reasons. A contrarian is a person who takes an opposite or challenging view, while a doubter and skeptic express uncertainty or doubt about something. An opponent is someone who opposes a particular ideology or philosophy.