Leo 54 was bishop of Kissamos in Crete; in 787 he attended the Second Council of Nikaia (the Seventh Ecumenical Council) and is attested at the fourth and seventh sessions, on 1 October and 13 October 787; he was perhaps present at the last five sessions, from 1 October to 23 November 787: Mansi XIII 145-486. In the list of those present at the seventh session he is styled Λέοντος ἐπισκόπου Κισσάμου: Mansi XIII 369. Elsewhere he is styled Λέων ἐπίσκοπος Κισσάμου or similar: Mansi XIII 145, XIII 392. At the fourth session he subscribed the statements read out from the Fathers in support of the veneration of icons: Mansi XIII 145. At the seventh session he subscribed the statement of the faith adopted by the Council: Mansi XIII 392.

(Publishable link for this person: )