Egeria, in Roman religion, a water spirit worshiped in connection with Diana at Aricia and also with the Camenae in their grove outside the Porta Capena at Rome. Like Diana, she was a protectress of pregnant women and, like the Camenae, was considered prophetic. Traditionally she was the wife, or mistress, and adviser of King Numa Pompilius, who established the grove at Rome and consorted with her there.