Dead Man's Hand

The Killing
At 3:10 on the afternoon of August 2, 1876, Jack McCall shot and killed James Butler Hickok from behind while the latter was playing poker in Deadwood's Saloon No. 10. He confessed to the authorities later that he had been paid to shoot Hickok

Hickok held the "Dead Man's Hand" at the time

Dead Man's Hand in Doomtown.
In Doomtown, Dead Man's Hand, the best possible hand -- with a Rank 11! -- is the two black Aces, the two black Eights and the Jack of Diamonds.

from the doomtown card

The true composition of the hand
J. Johnson, while cleaning the poker table after the body was removed, discovered a jumble of cards scattered over the floor. From them he kept the five that were more bunched together than the others, forming a hand. Recognizing the historical importance of the cards, Johnson secreted them in a pocket. They were later stolen from him at a drinking party. The present whereabouts of the cards are a mystery so the composition of the Dead Man's Hand can't be proven beyond doubt

In The Legend of Wild Bill Hickok Loren D. Estleman claims that Dead Man's Hand was the Ace of Clubs, the Ace of Diamonds, the two black Eights, and the Queen of Hearts

from the cover of the book

And, further, that the Ace of Diamonds had a heel mark in it, and that the Queen of Hearts was spoiled with a spot of blood

The Real West, a documentary broadcast on the History Channel in Los Angeles in the spring of 1998, claims that the odd card was a Queen of Spades

A display in the cardroom of the Midnight Rose casino in Cripple Creek Colorado

poker chip from the cardroom

cites four conflicting sources:

The Play "Dead Man's Hand" referencing Aces, Eights and the Jack of Spades
The publication #10 Saloon listing black aces, black eights and the Nine of Diamonds
A Gold Rose Casino flyer showing red aces, one black and one red eight and no odd card
A man known as HC said to know that the cards were the black aces, the Eight of Hearts, the Eight of Clubs and the Queen of Spades