As Irishgit mentions, Siegel is famous (or infamous) for "inventing" Las Vegas, but this is mythology. If there is such a person who can claim to have "invented" Vegas, it's probably Billy Wilkerson, the publisher and owner of the Hollywood Reporter. A degenerate gambler himself, he allegedly envisioned Vegas as the sort of gambling paradise/playground that it ultimately became. Apparently, people connected to Siegel heard about Wilkerson's plans, reported them to Siegel, and Bugsy muscled his way into the project. Reportedly, Vegas didn't really start to take off as a popular gambling resort until Siegel was assassinated in 1947. What always interested me about Siegel was the contrast between his reported charm and likeability and his brutality. He was known as a cold-blooded, fearless killer, and was an intimate of such men as Lucky Luciano, Meyer Lansky, and Lepke Buchalter. Supposedly, he off-handedly admitted to a straight citizen he knew that he had killed 12 people during his criminal career, and when he noticed the stricken look on the citizen's face, laughed and said, "Don't worry; there's no chance that someone like you would get hurt. We only kill each other." He was sent to California from NY in the mid 1930's as an emissary, and reportedly became involved in labor racketeering at the movie studios, extortion and drug smuggling. He was movie-star handsome, and a friend of such actors as George Raft, Clark Gable, and Jean Harlow. The house where he was shot in Beverly Hills (it was being rented at the time by his mistress Virginia Hill, who was conveniently away on vacation in Paris when Bugsy met his end there) is still standing and still looks amazingly like it did in 1947 (I have a picture of myself standing in front of the house, a shite-eating grin on my kisser). There are different theories as to why Siegel was assassinated, the most probable reason being that he was skimming money from his associates in NY. He was buried in the Jewish section of what's now known as the "Hollywood Forever" cemetery, not far from Paul Muni and Mel Blanc. There aren't a great many worthwhile books on Siegel; 2 that I can recommend are "The Man Who Invented Las Vegas" which is more about Billy Wilkerson than it is about Siegel but is still interesting, and "We Only Kill Each Other" by Dean Jennings, which is a bit dated and superficial but contains a lot of what appears to be accurate information and research. There's also "Little Man" by Robert Lacey, which is a biography of Siegel's friend Meyer Lansky but also contains some fascinating insights into Siegel. I don't recommend the Warren Beatty movie, although the "Moe Greene" character from "The Godfather" is supposedly based on Siegel.

I kind of see the fasciantion with them but still have always felt these A list criminals received too much noteriety.  As these psychopaths go; he was at least one of the better looking ones anyway. Apparently, he didn't care for the nickname "Bugsy" but, it was probably more appealing than one he could have been christened with following his murder - Popeye. Of course, by that time it was a moot point.

High living, womanizing, erratic, and violent.  Was likely part of the group that clipped Sal Maranzano during the Castellamarese War and was one of the founders of Murder Inc.

His primary claim to fame is "creating" Las Vegas, which is something of a myth.  Vegas existed before Siegel, and in fact his foray there was not an unqualified success.  The Flamingo actually lost money and closed about a month after Siegel opened it.  His syndicate sponsors, understandably perturbed that they had pissed six million dollars down a rat hole in the desert, had him clipped.