stubborn person; obstinate person; pig-headed person
Describes a person who is unyielding and refuses to change their mind, often with a negative connotation.
He's a stubborn person, so once he decides something, he never backs down.
あの頑固者を説得するのは無理だ。
It's impossible to persuade that obstinate person.
頑固者 describes someone stubborn in general, while 分からず屋 specifically stresses an unwillingness or inability to understand others' point of view.
頑固者 directly means 'a stubborn person,' overlapping closely with the idiomatic sense of 石頭 but with less colorful imagery.
Compound of 頑固 (stubborn) and 者 (person).