Source: dc.wikia.com

4. Major Disaster

Sometimes you don't become a supervillain because you were smart. Sometimes you become a supervillain because other people were dumb. So was the case for Paul Booker.

Paul was a standard criminal with nothing special about him. Then one day, while fleeing from the police, Paul broke into a house to hide. The house, as it turned out, belonged to Thomas Kalmaku, Hal Jordan's mechanic and Green Lantern's sidekick. While hiding there, Paul accidentally tripped a mechanism that opened a secret panel. Hidden in a secret compartment was a diary Tom was keeping of all Green Lantern's adventures. And it contained Green Lantern's secret identity because Tom is a moron. Oh, and it also contained The Flash's secret identity because Tom is a double-moron.

So Paul hired a bunch of criminal scientists to make him some supervillain gear, because why build it when you can buy it? Using devices to cause natural weather phenomena, he dubbed himself Major Disaster and set out to publically expose Flash and Green Lantern's secret identities. And all because Tom Kalmaku couldn't stop from scrapbooking top secret information.

Nice job, Tom.