truther

Someone who tells the truth.

A liar can't begin to start the riots a truther can.

Someone who believes that the US government was responsible for the 9/11 attacks.

[signed] 9/11 Truther

Therefore, virtually every press release or statement about 9/11 should include a reference to the poll to show people that many Americans are 9/11 truthers who scoff at the 9/11 Commission as a fraud and that demand a real 9/11 investigation.

A conspiracy theorist who does not believe the accepted story about some significant event, fact, etc.

For instance, "truthers" who believe in a US government conspiracy to destroy the pentagon

Rather, believers of this conspiracy theory (known as Sandy Hook “truthers”) propose that the entire event might have been staged by Homeland Security and FEMA

An advocate, especially for a headcanon.