Jon Havtoresson (born about 1312, died July 19 1395) was the son of knight Havtore Jonsson and princess Agnes Håkonsdatter, illegitimate daughter of King Håkon V Magnusson.
They were grandsons of King Håkon Magnusson, and through his father Havtore they belonged to the Sudrheimætten (Sørum - family), a powerful family of Romerike who were probably descendants of Bård Guttormsson on Rein, and perhaps also Harald Gille.
When his father Havtore died, Jon, who was probably the eldest of the brothers, inherited the farm Skea, with several properties in Solør and Odalen.
The daughter Cecilia was married to the Swedish-born knight and councilor Ulv Holmgeirsson.
Through his son Brynjolv, the now living Swedish noble family Roos af Hjelmsäter in direct male line from Jon.