In medieval Wales the descriptive word llwyd, meaning "grey," was corrupted to Lloyd, and since the double "ll" sound in Welsh is so hard to make if you don't have a handle on the language, it came out Floyd for English speakers.
The namesake that comes to mind first is boxing champion Floyd Mayweather, who is a junior. The story on his name isn't clear, but because we know he is Floyd Jr., we can assume his father was named Floyd because it was a moderately popular name in the year he was born, 1952. It ranked in the top 100 in 1886, 1889, and 1893. In 2015 it was given to 107 boys, a far cry from the 1,864 boys given the name in 1952. However, there is a chance Floyd Sr. was named after boxer Floyd Patterson, who won the Olympic gold medal in the middleweight division the year 1952.
There has been a hurricane Floyd, tropical storm Floyd, and two songs with the name. Over a dozen places in the U.S. are named Floyd. Pink Floyd is an English progressive rock band. There are dozens of namesakes for Floyd, including bronze Olympic medalist Floyd Simmons for the decathalon, football player Floyd Little, country musician Floyd Tillman, blues singer Floyd Jones, another boxer named Floyd Favors, and "Mickey Mouse" comic strip cartoonist Floyd Gottfredson.
In fiction there is Floyd Lawton, or Deadshot, from DC Comics, similarly named Floyd Lawson from the "Andy Griffith" TV show, and Floyd Pepper from "The Muppet Show."