William Clifford was a mathematician who lived in England at his death. His work on non-Euclidean geometry had a critical role in developing Einstein’s Theory of Relativity, which was named after him. Clifford algebras and his work on quaternions and biquaternions were some of the things for which he was well-known. Clifford suffered several nervous breakdowns, most likely caused by his excessive workload, and he succumbed to TB, which caused his death.
Yutaka Taniyama was a Japanese mathematician who, unfortunately, committed suicide on November 17, 1958, at thirty-three.