Xirinius was a gorillas who tried to recapture the escaped Taylor as he ran amok in the Ape City, using his net to trap him. He was also one of the apes tracking Taylor in the Forbidden Zone, under the command of Marcus, and was ordered by Zaius to silence Cornelius as the cave was being destroyed.
- Unusually, the name 'Xirinius' does not appear in either the movie or in any known script, though the final shooting script does describe at length the ape with the net as being 'a mounted cop' (the apes who finally take Taylor into custody identify themselves as 'security police'). The name may be an invention of Marvel Comics' writers.
- A character with same name later appeared in the Marvel-created story 'Kingdom on an Island of Apes'.
- The character was revived for the 2018 novel Death of the Planet of the Apes, in which Xirinius is second-in-command of the Security Police under Chief Cerek (Cerek is Marcus' successor).
- Planet of the Apes Magazine: Planet of the Apes
- Adventures on the Planet of the Apes: Planet of the Apes
- Death of the Planet of the Apes