Thomas Wallensis (died 1255) was a Welsh Franciscan, archdeacon of Lincoln and then bishop of St. David's.
Thomas was a canon of Lincoln Cathedral in 1235, when he witnessed a charter of Robert Grosseteste's.
He entered the Order of Friars Minor after their arrival in the country about 1237 and became one of the first four Franciscans to teach at the University of Oxford.
[3] While he was regent master in theology at the University of Paris in 1238, Grosseteste offered him the archdeaconry of Lincoln with a prebend.
He was present at the parliament in London, Easter 1253, and joined in excommunicating violators of Magna Carta.