- Iðga = Nuthatch.

- Iðja = Work

- Iðunn = Norse goddess, wife of Bragi. "She keeps in her box the apples which the gods are to eat when they grow old; in this way they will become young again, and so it will go on until Doomsday". (SnE)

- Igla = Smoke; name for a harmful creature.

- Ilmur = Norse goddess; scent.

- Íma = The grey or dark one, she-wolf. Name of a fairy in Icelandic folk tale. Suitable as a name for a dark grey mare.

- Imd = Giantess, hoyden. Suggests dark colouring.

- Ípa = One of Grýla's daughters: troll-women.

- Irpa = The bay one, sister of Þorgerður Holgabrúður. Their brother was called Sóti. The were great favourites of Hákon Hlaðajarl and others from the Háleygja family.

- Ísafold = Iceland.

- Ísing = Thin covering of ice.

- Ísold = Tristram's beloved. In the Icelandic saga of the lovers, the woman is named Ísodd, and is described as follows:  "She was more beautiful than any woman; she was so lovely that men saw no imperfection in her, and if one can assume to say it, people seemed to see rays of light shining from her eyes and face. She had so much hair that she could hide herself completely with it when she undid its gold claps. Her hair was more beautiful than gold just as gold is more beautiful than iron".

- Íviðja = Troll-woman.