Námo:

One of the Valar, Námo is most often named Mandos, though that is the name of his place of dwelling.

Nob:

One of the hobbits working for Barliman Butterbur at the Prancing Pony Inn at Bree. It was Nob who gave Sam the apples, one of which he threw at Bill Ferny.

Nienor:

The sister of Túrin, Nienor was born in Dor-lómin. At the age of twenty, she ventured with her mother Morwen, to Doriath, where her brother had been fostered. When her mother journeyed to Narogthrond, she went in disguise. After Glaurung cast a spell on her making her forget who she was, she was found by her brother. Neither recognized the other and she eventually married Túrin, who had called her Níniel, Tear-maiden. When Túrin killed the dragon, the spell fell away and Nienor knew who she was and whom she had married. In despair she threw herself off a cliff.

Nessa:

One of the Valar, Nessa is the sister of Oromë. She delights in deer and dancing. She married Tulkas.

Nori:

One of the thirteen dwarves who participated in the Quest of Erebor. Nori survived the experience and the War of the Ring. There is no information on when he died.

Nienna:

The sister to Námo (Mandos) and Irmo (Lórien), Nienna from the beginning in the Music sorrowed for the hurts of the world. She teaches pity and healing. Nienna remains unmarried.

The Lord of the Rings
The Silmarillion
The Hobbit
The Complete Guide to Middle Earth by Robert Foster