HAITO (HATTO). — Bishop of Basel, born into a noble Swabian family in 763. At the age of five he was received into the monastery of Reichenau, where he made great progress in his studies, so much so that Abbot Waldo (786–806) placed him in charge of the monastic school. When Waldo was transferred in 806 to the Parisian abbey of Saint-Denis, Haito succeeded him; but almost simultaneously he was also made Bishop of Basel.
He displayed great zeal in the reconstruction of the cathedral and in the reform of the clergy; he also rebuilt the abbey church of Reichenau. Charlemagne, who held him in high esteem, entrusted him in 811 with a diplomatic mission to Constantinople. Due to illness in 823, he resigned from his double office as bishop and abbot and spent the rest of his days as a simple monk at Reichenau, where he died on 17 March 836.
He wrote several works, including the Hodoeporicon, a kind of diary of his mission to the East; the Libellus de visione et obitu Wetini monachi Augiensis (PL 105, 771–80; MGH, Poetae Latini medii aevi. Poetae Latini aevi Carolini, II, pp. 267–75), which might be counted among the sources of the *Divine Comedy*; and the Capitulare of his diocese (PL 105, 763–68; MGH, Legum Sectio II Capitularia Regum Francorum, I, pp. 363–66; Mansi, XIV, 393–98).