Gregorio Paltrinieri (born 5 September 1994) is an Italian competitive swimmer. He is the Olympic and world long course and short course champion and three-times European long course champion in the 1500 m freestyle event at the 2012, 2014 and 2016 European Aquatics Championships, and two-times European long course champion in the 800 m freestyle event. Paltrinieri is the current 1500 m freestyle (short course) world record holder. He also holds the long course European records in the 800 m and 1500 m freestyle events with times of 7:39.27 and 14:34.04.
Paltrinieri started swimming at a very young age, and until the age of 12, he specialized in breaststroke. However, as he grew, he converted to freestyle, specializing in the longer pool distances.
His first international success came as a 16-year-old at the 2011 European Junior Swimming Championships in Belgrade, where he won the 1500 metres gold and an 800 metres bronze. Having qualified for the World championships in Shanghai, he did not progress further than the heats, but a few weeks later at the World Junior Championships in Lima, Peru, he was back on the podium with a 1500 metres freestyle silver and an 800 metres bronze.