Lydia Alice Jacoby (born 29 February 2004) is an American competitive swimmer specializing in breaststroke and individual medley events. Born and raised in Alaska she burst onto the international competitive swimming scene in 2020 and 2021 with personal best times in the 100-meter and 200-meter breaststroke events that put her in the rankings with former Olympic gold medalists and world record holders in the events. 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. She was the second Alaska-born athlete to qualify to compete at a Summer Olympic Games in any sport.