Collision of the Fandoms

It's eight o'clock in the morning. You have just woken up, and are pouring yourself a bowl of cereal when the doorbell rings. Three people are standing at the door. Each one asks you a question. You can only say 'yes' to one of them.

This guy

steps out of his box and asks you to be his companion.

This guy

tells you you're a wizard and asks you to come with him to Hogwarts.

This guy

asks you to be his flatmate and help solve some kind of mystery...thing.

You can choose only one.

WHO WILL IT BE?