Smile.dog

Smile.dog is a demonic dog that has mind-manipulating abilities. If someone sees a picture of Smile.dog, they will be forever haunted by him in their dreams. Every night, he will appear in their dreams, telling them to 'spread the word', i.e. show someone else the picture. If they follow out his orders, he will stop haunting them. He often drives his dreamers to suicide.

Original Creepypasta
Knowledge of Smile.dog's existence was brought to the attention of non-dreamers through this documentation of a dreamer's first encounter with smile.jpg.

History
Smile.dog is believed to be a fugitive from Hell itself, although it is not known what his role there was or what caused him to leave, as Smile.dog has given no further information on his past. It is possible that in future episodes his past will be explored more deeply.

At some point after leaving Hell, Smile.dog encountered Slenderman. The two have since become inseperable friends.

Personality
Smile.dog is a talking dog. He is a very lax, go-with-the-flow sort of person, and the first to warm up to Gary.