When in human form, Apocryphos takes the appearance of a thus far unnamed Cardinal with lightly-colored (brown in the anime) hair and glasses(which he doesn't need). He wears the same black cassock seen on the other Central, Vatican officials that he presumably arrived with but does not wear the clerical collar, having only a rosary around his neck. Over his uniform he wears a long, lighter-colored coat.
In his true form, Apocryphos' body is entirely white and somewhat cracked in appearance. He is hairless, noseless and his sclera becomes dark red while his irises turn to light green. Inside the Iris, a red slit shines. He possesses a cross similar in size and shape to the one on Allen Walker's hand on his upper chest. He is taller than Tyki Mikk who is already a tall individual.
While in human guise, Apocryphos is amiable and friendly, seen comforting Allen Walker's friends when they are harassed in the cafeteria by those who think Allen should be executed, the Cardinal assuring the group that Allen would not be executed.
Once he reveals his true form, Apocryphos becomes ruthless and obsessed with protecting the Heart. He bears a deep hatred for the Noah, and a deep desire to merge with Allen and his Innocence. He also showed great anger when Allen expressed disgust at Apocryphos' attempt to merge with him.
Apocryphos is a calm creature both in disguise and when he shows his true nature. He is completely driven by his purpose and acts as a juggernaut. He dislikes anything that can be a threat to the Heart's accomodator.