Sir Thornberry is a character from the animated series Disney's Adventures of the Gummi Bears.
Sir Thornberry is a Gummi Knight who resides in the Gummi capital of Ursalia. When the Great Gummis were forced to abandon their home due to the actions of humans, he was left behind as a caretaker. This was just in case the Great Gummis were ever able to return, similarly to the Gummi Glen Gummis.
While brave and honorable, he is a bit scatterbrained as a result of being on his own for so long.