Fallout 3 and Fallout: New Vegas
Fallout 4 and Fallout 76
The perk got expanded to three ranks, and has been modified so that killing an enemy in V.A.T.S. is no longer guaranteed to restore Action Points. Instead, the perk grants a percent-based chance to restore all Action Points upon killing an enemy in V.A.T.S., with the percentage increasing with each rank.
Fallout: The Roleplaying Game
A perk that grants one additional roll, with a chance to restore Action Points if an Effect was rolled.
Fallout: The Board Game
A perk that grants one additional action when discarded.
Behind the scenes
Grim Reaper's Sprint was originally a fan-created perk and winner of the Fallout 10th Anniversary Contest in 2007, submitted by Marc-Andre Deslongchamps. Bethesda implemented the perk in Fallout 3, describing the idea as "elegant and simple" while affecting game mechanics in a unique way.