Palatinate-Birkenfeld (German: Pfalz-Birkenfeld), later Palatinate-Zweibrücken-Birkenfeld, was the name of a collateral line of the Palatine Wittelsbachs. The Counts Palatine from this line initially ruled over only a relatively unimportant territory, namely the Palatine share of the Rear County of Sponheim; however, their importance steadily grew. All living members of the House of Wittelsbach descend from Palatinate-Birkenfeld, which thus became the parent branch of the Kings of Bavaria.