according to le reddit:
Fate/stay night: Unlimited Blade Works [2014] [Season 1 and Season 2].
Fate/stay night: Unlimited Blade Works 2nd Season - Sunny Day [This an OVA and should be watched after finishing the UBW show.]
Fate/stay night: Heavens Feel [Film 1, Film 2, Film 3]
Fate/Zero [ Season 1 & 2]
This series is the prequel to Fate/Stay Night. It takes place 10 years before the events of Fate/Stay Night.] (the prequel is meant to be watched after finishing Fate/Stay Night and not before! People always make a mistake of watching Fate/Zero first, but that spoils plot events in Fate/Stay Night, so make sure to watch Fate/Zero AFTER finishing all of Fate/Stay Night.)
- Lord El-Melloi II Sei no Jikenbo: Rail Zeppelin Grace Note
The series takes place 10 years after the events of Fate/Zero and 2 months before the events of Fate/Stay Night and revolves around the Clock Tower in the United Kingdom.
https://www.reddit.com/r/fatestaynight/comments/df8rvo/rfatestaynights_official_viewing_order_guide_v2/
