Ryan Lochte won his fifth and sixth golds at the 2012 world short course championships on Sunday, taking his toll to eight in all for the week and 30 in his career.
Lochte won the 100m individual title in 51.21sec ahead of Australia's Kenneth To with George Bovell of Trinidad in third.
The 28-year-old New Yorker then anchored Matthew Grevers, Kevin Cordes and Thomas Shields to 4x100m medley relay gold in 3min 21.03sec, ahead of Russia and Australia.
Lochte had already won the 200m freestyle, 4x100m freestyle relay, 4x200m freestyle relay and 200m individual medley titles, adding silver in the 200m backstroke and bronze in the 100m butterfly for good measure.
He was also the only swimmer to set world records in Istanbul -- in the semi-finals of the 100m medley and final of the 200m medley.
Lochte, a five-time Olympic champion, and the heir to the now-retired Michael Phelps, the greatest Olympian of all time, is the only swimmer in history to win eight medals at the same world short course championships.
His career total now stands at 30 medals of which 20 are gold.
"I swim in a bunch of races but that's what I train for. I like change and that's why I want to do everything," said Lochte.
"For me, this is fun in the sport of swimming. I train for everything. I push my body to limits other athletes are afraid of. That's why I am able to swim two races in 30 minutes."
The United States ended the five-day championships with 27 medals, 11 of which were gold, ahead of China with 11 medals including three gold.
Hungary were third in the table with a 10-medal tally of which three were gold.
Russia's Vladimir Morozov gave notice of the danger he will pose at the Rio Olympics in 2016 when the 20-year-old, Los Angeles-based Siberian won the 50m and 100m freestyle.
Morozov defeated France's Olympic champion in the 50m freestyle in a time of 20.55sec against 20.88sec.
In the 100m, his winning time was 45.65sec to finish ahead of Australia's Tommaso d'Orsogna in 46.80sec.
Hungary's Laszlo Cseh, a multi-medallist in the Olympics and world championships, is still waiting for his first short course title after finishing second to Japan's Kazuya Kaneda in the 200m butterfly on Sunday.
In the women's events, the week's two stars, Ruta Meilutyte, the 15-year-old Lithuanian, and 16-year-old Chinese sensation Ye Shiwen didn't swim Sunday.
Meilutyte left Istanbul with three medals -- gold in the 50m and 100m breaststroke and silver in the 200m individual medley.
Ye, a double Olympic gold medallist, took gold in the 200m medley and silver in the 400m medley.
American triple Olympic champion Allison Schmitt took the 200m freestyle gold on Sunday.
Ryan Lochte of the US competes in the 100m medley final during the short course swimming world championships in Istanbul on December 16, 2012. Lochte won his fifth and sixth golds at the 2012 world short course championships on Sunday, taking his toll to eight in all for the week and 30 in his career.