Tom O'Brien was a race rider. Many in the racing industry mourn his death at 39 after a cancer diagnosis. The Racing Post called him a fantastic person. O'Brien secured victories at the Cheltenham Festival. The Guardian and 7NEWS reported his death after a courageous fight with cancer. At Bangor, a close friend called him a hero and a brilliant rider. Yahoo News Australia said O'Brien was the another rider to die in a short span. Tributes continue in the world of horse racing.