Lagadha (fl. c. 1st millennium BCE), also known as Lagadh Acharya, was an ancient Indian astronomer and mathematician. He is celebrated as the author of the Vedanga Jyotisha, one of the earliest known Indian treatises on astronomy and timekeeping. His श्रीलगधाचार्यविरचितानि ज्योतिस्सूत्राणि (Jyotis Sutrani of Sri Lagadhacharya) details methods for calculating celestial phenomena and determining auspicious times for Vedic rituals.