Catellus of Castellammare was a 9th-century bishop who served the community of Castellammare di Stabia. A close companion of Saint Antoninus of Sorrento, he reportedly sought a life of solitude as a hermit. This desire led him to temporarily resign his episcopal office to Antoninus, before eventually returning to his duties. His life, characterized by a struggle between ecclesiastical responsibilities and the wish for asceticism, is documented through late ninth-century chronicles and accounts of his contemporary, Antoninus.