In a D&D campaign I ran back in the late '70s (while still a callow teen) I had a player that was a Druid who refused to eat plants because they were sacred.
ETA: and in a Runequest campaign a character that fought and killed a bear only to discover that she had a cub, which he took under his wing and raised, only to be killed by it later when it grew up because it’s a wild fucking animal (I was always rolling behind the scenes to see if it was time for the turn)
