- "Congratulations! I'm delighted to welcome you to SLYTHERIN HOUSE. Our emblem is the serpent, the wisest of creatures; our house colors are emerald green and silver, and our common room lies behind a concealed entrance down in the dungeons. As you'll see, its windows look out into the depths of the Hogwarts lake. We often see the giant squid swooshing by – and sometimes more interesting creatures. We like to feel that our hangout has the aura of a mysterious, underwater shipwreck."