Thomas of Celæno, also known as Thomas of Celano (around 1200 - around 1255), was a Franciscan monk and hymnodist from Italy whose chief claim to fame is his reputed authorship of the Dies Iræ.
Thomas was one of the first disciples of St Francis of Assisi and joined the order around 1215. In addition to the sequence Dies Iræ, Thomas also wrote two lives of St Francis, a life of St Clare of Assisi, and at least two more hymns praising St Francis.