He's '(as) stubborn as a mule'. [=he's very/extremely stubborn]
She 'has a stubborn streak'. [=she is often stubborn]
She's wrong, but she's too 'stubborn' to admit it.
(..) To rule the North. I wish I could fight beside you. Believe me, I do. But I swore a sacred vow at the Godswood. I pledged my life to the Night's Watch. You're as stubborn as your father. And as honorable. I can imagine no higher praise. I didn't mean it as praise. Honor got your father killed. (..)2015 TvShow: Game of Thrones Title: High Sparrow Season: 5 Episode 3