Nuna

Nuna is the ship between Neville Longbottom and Luna Lovegood from the Harry Potter series.

Canon Relationship
They first met on the Hogwarts Express, in 1995. Neville found Luna a bit "odd", as she believed in the existence of strange, mythical creatures, had a tendency to read magazines upside down, and wore earrings that appeared to be made of radishes. Luna and Neville she fought alongside each other at the Battle of the Department of Mysteries, the Battle of the Astronomy Tower and the Battle of Hogwarts. At some point they became very close friends. During Neville's last year at Hogwarts, he, Luna and Ginny, re-formed and co-led Dumbledore's Army in order to oppose the Carrows. Neville seems to have a place in his heart for Luna, they also remained close friends in later life. It seemed that Luna was always glad when Neville, Ginny, Hermione, Ron and Harry were close by, proved when the trio visited Luna's father Xenophilius Lovegood and seeing Luna's room with their painting on her bedroom wall connected with gold letters spelling friends.

Behind the Scenes
J.K Rowling was asked in an interview if they ever would become a couple she replied "Definitely Not". However, as time went by Rowling started to "feel a bit of a pull" between the unlikely pair.

Ultimately, Rowling left the question of their relationship open at the end of the book because doing otherwise "felt too neat."

In later interviews, Rowling debunked the ship confirming Luna married Rolf Scamander and Neville married Hannah Abbott.

Trivia

 * Both Luna and Neville (as well as Harry) have the ability to see thestrals.
 * Both Luna and Neville joined Dumbledore's Army.