Dallas Genoard

A man who, despite the fact that he is an infamous and volatile delinquent, has a loving sister, Eve Genoard, that is one of his few weaknesses.

In 1930, Dallas, after mugging an old man (named in the anime as "Mr. Barnes"), unknowingly steals two bottles of the Grand Panacea that the immortal Szilard Quates had developed using Barnes. He mistakenly leaves them at the Gandor brothers' hideout after being beat up by Berga Gandor, but Ennis, Szilard's homunculus, regardless, apprehends Dallas as he's beating up Isaac and Miria on the street for running into him. (This seems to be an offense that irks Dallas without fail...)

While Dallas is unconscious, Szilard has Ennis inject Dallas and his thugs with the incomplete Panacea, which allows them to be indestructible like the other immortals, but aging continues and will eventually be the death of them. Szilard uses Dallas, who is eager for vengeance against the Gandors, to steal back the elixir before he plans to devour him. However, while the Gandor brothers are away, Dallas, now cockier than ever with his newfound abilities, shoots up the place and kills four of the Gandors' men. (In the light novels, Luck mentions them to be some of his closest friends.)

However, with a seemingly uncanny knack for catching the worst luck, Dallas loses the elixir to Isaac and Miria, who thought he was hauling something valuable.

In the end, Dallas, after being hit by a car Issac and Miria stole and were driving, wakes up in an oil drum, captured by the Gandor brothers. Since they were aware of his deathless state, the Gandors decided that the only way they could be rid of Dallas was by cementing him in the barrel and sinking him into the bottom of the Hudson. That seemed to be the end of Dallas...

However, in 1932, when Eve, with the help of the Runorata family, dredges the river bottom and come up with the drum Dallas was trapped in. But, when they opened it, they realized he wasn't in there... Only broken concrete and playing cards remain. Neither the novels nor the anime reveal what happened to Dallas after that.