The Raman effect was discovered in 1928. It was “first reported by Raman and his coworker K. S. Krishnan,” Wikipedia notes, and it calls Krishnan a co-discoverer. The effect carries Raman’s name. In 1930 Raman received the Nobel Prize in Physics for it.
According to the magazine Madras Musings, Raman once told Sukumar Sircar that Krishnan deserved half the credit for the discovery.