Halloween-themed trail races through Murphy-Hanrehan Park Reserve, with 5K, 10K, 25K, marathon, 50K and 50-mile distances on mostly trail with some single track. The 50-miler starts at 6 AM and the 50K at 7 AM, and most prizes go to the best costumes. Online registration runs through Oct. 16, from $85 for the 5K to $140 for the 50-miler.