Metal Keychain - Officially Licensed Harry Potter House Slytherin Crest Emblem measures approximately 1 3/4" Slytherin produces more than its share of Dark wizards, but also turns out leaders who are proud, ambitious and cunning. Merlin is one particularly famous Slytherin. This green and black tone, shield-shaped Harry Potter Slytherin Keychain features the signature Slytherin Snake on his green and black heraldic background, attached to a sturdy D-ring metal keyring.