Oddone di Monferrato (died before 23 January 1251) was an Italian papal diplomat and Cardinal. He was of the noble house of Monferrat, son of Marquis Guglielmo VI de Monferrato.
He was created Cardinal in 1227. He undertook numerous missions as papal legate for Pope Gregory IX in northern Europe, including mediation between the Archbishop of Canterbury and Archbishop of York in London in 1237. In English history he is usually known as Cardinal Otto. When in July 1237 he came to Osney Abbey, a brawl broke out between a group of scholars from the university and the cardinal's men in which the legate's cook was killed. Otto himself was locked for safety in the abbey tower, emerging unscathed to lay the city under interdict in reprisal. In 1240 he visited Shaftesbury Abbey and confirmed a charter of 1191, the first entered in the Glastonbury chartulary.
He became Bishop of Porto e Santa Rufina in 1244.
- ^ Othon de Montferrat, Ottone Candido, Otto of Toneno, Ottone da Tonengo.