Passage: Jack William Nicklaus (born January 21, 1940), nicknamed The Golden Bear, is an American retired professional golfer. In the opinion of many observers, he is the greatest golfer of all time. During a span of more than 25 years, he won a record 18 major championships, three ahead of Tiger Woods (15). Nicklaus focused on the major championships—Masters Tournament, U.S. Open, Open Championship and PGA Championship—and played a selective schedule of regular PGA Tour events. He has competed in more major championships (164) than any other player. He finished with 73 PGA Tour victories, third on the all-time list behind Sam Snead (82) and Tiger Woods (81).

Question: Who is Jack Nicklaus?
an American retired professional golfer