coauthor; collaborator; joint author
Refers to a person who jointly writes or creates a work with others, typically in academic, literary, or professional contexts.
He is a coauthor of that paper.
This book was written by three joint authors.
Compound of 共 (kyō, 'together') + 著 (cho, 'writing') + 者 (sha, 'person'). The reading is on'yomi throughout.