The rat pack were:

So yeah. One day in 1959, the five are seriously hung over and whatnot after a binge at The Sands Hotel and Casino in Las Vegas. Actress Lauren Bacall was kind enough to point out "You look like a ...Rat Pack". Sinatra then declared that they would hold their own "summit of cool". Vegas would never be the same.

For the next seven years, the five performed nightly at that casino. They were notorious for their womanizing and drinking. They became famous and everybody wanted to party with the guys. Ava Gardner, one of Frank Sinatra's wives, once stated that "he may weigh just 120lb, but 80lb of that was pure dick". Indeed, Sinatra once told Marilyn Monroe to get her "fat ass out of the room" during a poker game.

They had talent. They had voices. But the one thing they had that set them on top was style. Despite the non stop party, they were always clean cut, suits immaculate and shoes polished. They managed to make the world see them as nothing but class with cigarettes in their mouths and obnoxious jokes that would today be stomped on immediately as politically incorrect. Still, the men wanted to be them and the women wanted to be with them.

As they tend to do in life, things ended rather badly. Sinatra ended up in a fight with the management of the Casino after they cut his credit. Chairs and fists were thrown and Sinatra left the scene. Without him, the act was never the same.

Ironically, Sammy died of throat cancer, Frank of a multitude of ailments, Dean drank himself to death, and Peter ended up a junkie. Seems they paid for some earlier mistakes.

Films:

Sources:
http://www.theratpack.org.uk
http://www.geocities.com/Hollywood/Bungalow/3456/rat.html
http://www.cnn.com/SPECIALS/1998/sinatra/