Top of the list by a mile (nautical mile that is!):

Charles Herbert Lightoller - Second Officer on Titanic, Officer in the Royal Navy and general all-round hero; read his story, you won't be bored I assure you!

Wikipedia page Titanic & Other Ships

Others with military service

Okay, so now I'm struggling (can you help?).

Miriam Lightowler OBE JP - First lady Mayor of Halifax, amongst other firsts.

News page

Professor Marshall Lightowlers - a leader in the field of parasitology. Probably throws up more links for Lightowlers in Google than any other.

Wikipedia page

Nick Lightowlers aka Tesco - Founder member and lead singer of The Members punk band in the 1970s.

Wikipedia page