John Davis Gaughan, Sr. (October 24, 1920 – March 12, 2014) was a casino owner and operator from the early 1950s in Las Vegas, Nevada. He had an ownership stake in many casinos throughout his career, but he is best known for his ownership of the El Cortez, where he resided until his death on March 12, 2014. At one time Gaughan reportedly owned more than 25 percent of the available real estate in Downtown Las Vegas.