| Tora Mosterstong | |
| Native Name: | Þóra Morstrstǫng |
| Native Name Lang: | non |
| Spouse: | Harald I of Norway |
| Spouse-Type: | Partner |
| Issue: | Håkon the Good |
Tora Mosterstong (non|Þóra Morstrstǫng)—also known as Thora Mostaff—was one of Harald Fairhair's concubines and the mother of Håkon the Good; Harald Fairhair's youngest son and the third King of Norway (c. 935–961).
According to Snorri Sturluson's Saga of Harald Fairhair (Soga om Harald Hårfagre), Tora was from the island of Moster and was descended from the clan (ætt) of Horda-Kåre (Hǫrða-Kára):
Snorri consistently speaks of Tora as concubine and maidservant, which tends to produce the wrong connotations. Horda-Kåre was one of Harald Fairhair's old allies, and held high office at the Battle of Hafrsfjord. When Tora had a place with the king, it must have been part of a conscious policy to keep the two clans close.