With a pair of weekend retweets, President Donald Trump amplified another unfounded conspiracy theory. 

It was hardly the first time. His political career began the same way. While birtherism was Trump's most infamous conspiracy theory, it was far from his only one.

He has promoted dozens of outlandish claims, many of which are so blatantly untrue that they have not required even a cursory fact check to disprove.

Among his claims: