leader of a troupe
Refers to the head or leading performer of a theatrical or entertainment troupe, especially in traditional Japanese performing arts.
彼は歌舞伎の一座の座頭を務めている。
He serves as the leader of a kabuki troupe.
Compound of 座 (za, 'seat; troupe') and 頭 (kashira, 'head; leader'). The reading ざがしら is a rendaku form of かしら.