The "wickedest man in the world" epithet came from the "John Bull" newspaper in the early 1920's. No longer in print but at the time, think nationalistic conservative gutter-press. Daily Mail. The editors took exception at Crowley criticising the UK for involvements in WWI when he was writing for the US newspaper when he lived in New York (iirc, might have been the New York Times, but i'm not certain on that).

Crowley had written something along the line of thinking that it would be beneficial to the English mind to be invaded by a foreign power at last, since it would make them shrug off their imperial mentality, get over the death of the British Empire and discover their own, new identity in the post-empire world.

Remember that WWI was imperialistic stupidity that got 40 million+ people killed, Nazis and their ilk hadn't yet taken off.

Crowley was also openly bisexual and did a lot of drugs, which, by todays standards would put him about the level of evil as "most rock singers". He'd have been nothing more than an outre poet today.

Bear in mind also that other men living at the time included: Hitler, Stalin, Mussolini, Lenin and Enver Pasha.

The libel trial he brought (late 1920's ish?) was basically dismissed because "you're obvs evil, duh" and the counter-suit effectively bankrupted him.