Shikao Ikehara(池原 止戈夫,Ikehara Shikao?, April 11, 1904 – October 10, 1984) was a Japanese mathematician. He was a student of Norbert Wiener at MIT (PhD 1930). Ikehara, using Wiener's Tauberian theory, established the Wiener-Ikehara theorem, and derived a new proof of the prime number theorem. In particular he showed that the prime number theorem is equivalent to the non-vanishing of the zeta function on the line Re s = 1. Earlier proofs of the prime number theorem relied on the just mentioned non-vanishing property of the zeta function, together with some bounds on the order of growth of the zeta function. Returning to Japan after studying with Dr Wiener, he taught at Osaka University.