Fate series

The Fate series is a TYPE-MOON media collective that follows various events called Holy Grail Wars that involve Masters, generally accomplished magi, summoning Servants, Heroic Spirits, and battling each other until the last remaining pair can claim the purported Holy Grail. It began with the, Fate/stay night, and has since gathered a number of prequels, sequels, spinoffs, and adaptations bearing the same "Fate" name.

Connections
Fate/stay night, and Fate/hollow ataraxia are directly related, taking place in the same universe. The prequel work "Fate/Zero", while telling the story of the Fourth Holy Grail War 10 years prior to Fate/stay night, is treated as taking place in a very similar parallel world due to various differences in minor details and events. Fate/kaleid liner PRISMA☆ILLYA is a direct spin-off of Fate/stay night featuring characters from Fate/stay night, Fate/hollow ataraxia and Fate/Zero in a parallel world where the Fourth Holy Grail War was stopped before taking place.

Fate/Extra, its sequel Fate/Extra CCC, Fate/Extella, and the unrelated Fate/Apocrypha take place in similar universes that diverged from that of Fate/stay night at different points.