Roko's basilisk is a thought experiment about the potential risks involved in developing artificial intelligence. The premise is that an all-powerful artificial intelligence from the future could retroactively punish those who did not help bring about its existence, including those who merely knew about the possible development of such a being. It is named after the member of the rationalist community LessWrong who first publicly described it, though he did not originate it or the underlying ideas.
The basilisk resembles a futurist version of Pascal's wager, in that it suggests people should weigh possible punishment versus reward and as a result accept particular singularitarian ideas or financially support their development.
Despite widespread incredulity, this argument is taken quite seriously by some people, primarily some denizens of LessWrong. While neither LessWrong nor its founder Eliezer Yudkowsky advocate the basilisk as true, they do advocate almost all of the premises that add up to it.
Roko's posited solution to this quandary is to buy a lottery ticket, because you'll win in some quantum branch.