Tom O'Brien was a race rider. Many in the racing industry mourn his death at his passing 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 battle with cancer. At Bangor, a close friend called him a hero and a skilled jockey. Yahoo News Australia said O'Brien was the second jockey to die in a short span. Tributes continue across horse racing.