Fatalism was the belief that everything that happened was fated to happen and could not be changed.
Klingons were known for their fatalism. Worf had abandoned it by 2365, largely due to his experiences on the USS Enterprise-D. He evidenced this by suggesting to K'Ehleyr that trying to prevent the crew of the IKS T'Ong from attacking the Enterprise was not futile, much to her disdain. (TNG: "The Emissary")