Usain Bolt claimed a record third 100m title while tennis player Andy Murray won Britain's fifth Rio gold on GB's best day at an overseas Olympics.
A 15th gold of the Games, putting GB second in the medal table, followed gymnast Max Whitlock's historic double success and Justin Rose's golf victory.
Cyclist Jason Kenny defeated team-mate Callum Skinner for his fifth title.
South African Wayde van Niekerk broke a 17-year world record to win 400m gold in 43.03 seconds.
Bolt ran 9.81 seconds to beat Justin Gatlin to gold and follow up his titles at Beijing 2008 and London 2012.
Van Niekerk's 400m time was 0.15 seconds quicker than the previous world record set by Michael Johnson in Seville in 1999.
Wimbledon champion Murray retained his Olympic title with an epic win over Argentina's Juan Martin del Potro in the men's singles final.
Britain secured five golds, and their three silvers included one for windsurfer Nick Dempsey to keep the team on track for their Rio medal target of 48.
GB won six gold medals on 'Super Saturday' at London 2012 - the best one-day haul since eight were won in 1908.
Sailor Giles Scott is guaranteed gold in the men's Finn class after opening an unassailable lead before Tuesday's medal race, and boxer Joshua Buatsi will win at least a bronze.
But there will be no third Olympic medal for Christine Ohuruogu, champion in 2008 and silver medallist at London 2012. She hinted at retirement after missing out on the women's 400m final by finishing fifth in her semi-final.