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.
(..) I'm not good at counting. We're leaving too many behind. The free folk are stubborn. You know how long it took Mance to band them together? fucking years. And he knew them better than I ever will. (..)2015 TvShow: Game of Thrones Title: Hardhome Season: 5 Episode 8