Zachary Hammer (born May 29, 2006) is an American competition speed climber. He represented the United States at the 2024 Summer Olympics.
Hammer represented the United States at the 2024 Summer Olympics in the men's speed event. In August 2025, he competed at the 2025 World Games and won a bronze medal in the speed relay along with Sam Watson. The next month he competed at the 2025 IFSC Climbing World Championships and won a bronze medal in the men's speed event.