Tom O'Brien was a jockey. British and Irish racing communities mourn his death at his passing at 39 after a cancer battle. Many publications called him a remarkable individual. O'Brien won races at the Cheltenham Festival. The Guardian and 7NEWS reported his death after a courageous fight with cancer. At Bangor, a colleague called him a hero and a skilled jockey. Yahoo News Australia said O'Brien was the another rider to die in two days. Tributes continue across horse racing.