Blue Moon

Blue Moon was a blue-maned stallion originally from Trotsylvania who moved to Horseshoe Hill in Ponyville, Equestria. He was the boyfriend of North Star and father of Lilymoon and Ambermoon

History
Blue Moon dated North Star for "months and months" prior to his appearance at the Grand Galloping Gala, implying he may have had his daughters with another mare. He appeared to be quite wealthy, owning a mansion in Canterlot and attending the aforementioned Gala. He was originally from the region of Trotsylvania, a mysterious region with apparently creepy stories surrounding it. He eventually moved to Horseshoe Hill, a district of Ponyville but was deemed creepy.

Cartoon

 * "The Best Night Ever"
 * "Power Ponies"
 * "Equestria Games"

Novels

 * Ponyville Mysteries: Schoolhouse of Secrets​
 * Ponyville Mysteries: The Tail of the Timberwolf​
 * Ponyville Mysteries: Cursed Crusaders​
 * Ponyville Mysteries: Journey to the Livewood

Behind the scenes
Blue Moon's name was only given on a trading card, as he was otherwise a background character. He later appeared in the Ponyville Mysteries series of novels as a recurring figure.