Cogitosus (fl. c. 650) was an Irish monk and writer. Cogitosus was a monk of Kildare who wrote the oldest extant vita of Saint Brigit, Vita Sanctae Brigidae, around 650. There is a controversy as to whether he was related to Saint Brigit.
There are at least two contemporary English translations of Cogitosus's Life of St Brigid: one by Connolly and Picard in 1987 and another in 1993 by Liam da Paor.