Lydia Alice Jacoby (born February 29, 2004) is an American competitive swimmer specializing in breaststroke and individual medley events. When she was 17 years old, she won the gold medal in the 100-meter breaststroke and the silver medal in the 4×100-meter medley relay at the 2020 Summer Olympics, her first Olympic Games. She was the first swimmer from Alaska to qualify for an Olympic Games, qualifying for the 2020 Summer Olympics in the 100-meter breaststroke when she was 17 years old. Her gold medal in the 100-meter breaststroke at the 2020 Summer Olympics was the first Olympic medal won by a swimmer from the state of Alaska in the history of swimming at the Olympic Games.