The Snowman is a character and the main antagonist of the Christmas Special. He has an insatiable appetite for food (including human flesh) and grows bigger every time Sam, Taurtis, JTheStar and Grian feed him snowballs, food and other items.
In the finale to the Christmas Special, it is revealed that he is not merely a snowman, but actually "a being from space", and the snow falling around him is actually his biomass, in the form of snowflake drones.
After being destroyed by Sam and Dom with shovels (and after they realise that his power core is in his hat), he seems to reconstitute as a mini-snowman which is also destroyed. This later form is similar to another snowman that the boys found (and destroyed), who Taurtis assumed was The Snowman's cousin.
He's a snowman, built from what appears to be snow. The Snowman has two big black eyes, but his most prominent feature is his big mouth -- a big hole that can open and close like a real mouth, inside of which is a tongue made of red carpet. Behind the carpet is a big hole, which is most likely his trachea. The Snowman also wears a hat.
The Snowman is greedy and insatiable. He is also evil,manipulative and untruthful to lure in new victims and tricks them into doing his dirty deeds.
In part 3 of the Christmas Special, Dom reveals "I found him" in relation to the Snowman, and mentions that he kicked him (being punched in return).
The snowman uses the boys to get foods by lying about being their friends.