Opus

Opus is Agnes Day's dog. She thinks he's a German shepherd, but she doesn't know.

Agnes entrusts him to SMSC Agent Aladdin Sane during "Operation: Asterion," though she takes him back when she comes out of the labyrinth alive.

Trivia

 * Opus's full name (Opus Day) is a pun on the Latin phrase "Opus Dei," meaning "Work of God."