Charles Astor Bristed was an American scholar and author, sometimes writing under the pen name Carl Benson. He was the first American to write a full-length defense of Americanisms and is the earliest known person to use the term "conspiracy theory".

A conspiracy theory is an explanation for an event or situation that asserts the existence of a conspiracy by powerful and sinister groups, often political in motivation, when other explanations are more probable. The term generally has a negative connotation, implying that the appeal of a conspiracy theory is based in prejudice, emotional conviction, or insufficient evidence. A conspiracy theory is distinct from a conspiracy; it refers to a hypothesized conspiracy with specific characteristics, including but not limited to opposition to the mainstream consensus among those who are qualified to evaluate its accuracy, such as scientists or historians.