Answer: Roger Federer
Notes: Roger Federer is the male tennis player who won the most number of Grand Slam tournaments. Roger Federer is a Swiss professional tennis player who is ranked world No. 4 in men's singles tennis by the Association of Tennis Professionals (ATP). He has won 20 Grand Slam singles titles—tied for the most in history for a male player with Rafael Nadal—and has held the world No. 1 spot in the ATP rankings for a record total of 310 weeks and was the year-end No. 1 five times, including four consecutive.
