Garl is the brutal leader of the Khans by 2161, ruling his band of raiders with an iron hand after killing his father, the former leader. He leads them from an old ranch house in the middle of nowhere. He is descended from the population of Vault 15 and regularly raids Shady Sands for supplies.
Canonically, as established in Fallout 2, Garl is eventually killed by the Vault Dweller along with all other Khans in the Khan camp. Only one (which doesn't appear in Fallout), called Darion, continues the Khans legacy, carrying on in Fallout 2 as the New Khans.
If the Vault Dweller is male and has Luck greater than 8, there is a 50% probability that he will look like Garl's father, the original Death-Hand and original leader of the Khans. Everyone in the camp gets freaked out by the "ghost of Death-Hand" returning since Garl killed his father to gain control of the gang.