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.
(..) - Mom? - Bella? - Mom? - There you are. That's my favorite part. You were a stubborn child, weren't you? - She's not even here. - No. Sorry. You know, but you really made it too easy. So to make things more entertaining, (..)2008 Twilight