It's possible you're thinking of:
* Paris, who famously eloped with Helen, sparking the Trojan War. However, he wasn't specifically a "night rider" in the sense of a protector or companion. He was a Trojan prince who stole Helen from her husband, Menelaus, King of Sparta.
* The story of Helen and the Trojan War was told in various forms and versions, so perhaps you're referring to a less well-known detail or interpretation that doesn't have a consistent name or figure associated with it.
If you can provide more context about the source or where you encountered this term, it might be easier to understand what you're referring to.