Gangesha Upadhyaya (Sanskrit: गंगेश उपाध्याय, Gaṅgeśa Upādhyāya) (first half of the 14th century) was an Indian philosopher, logician and mathematician from the kingdom of Mithila. He established the Navya-Nyāya (“New Logic”) school.
His Tattvacintāmaṇi (The Jewel of Thought on the Nature of Things), also known as Pramāṇacintāmaṇi (The Jewel of Thought on the Means of Valid Knowledge), is the basic text for all later developments. The logicians of this school were primarily interested in defining their terms and concepts related to non-binary logical categories.