There is a total of 31390 clues beginning with on
- Only person to win both an Oscar and a Nobel
- Only person to win Emmys for acting, writing and directing
- Only person to win Oscars for acting and screenwriting
- Only person to win seven Super Bowls
- Only person to win the Nobel Prize in two different scientific fields
- Only person to win two Nobels in two different sciences
- Only person whose son and brother also won the Indianapolis 500
- Only pitcher of two consecutive no-hitters Johnny Vander ___
- Only pitcher to throw a perfect game in the World Series
- Only pitcher to win the deciding games of the ALCS, ALDS and World Series in the same year
- Only pitcher whose jersey number was retired by the Mets
- Only place great teams are unbeatable
- Only place in the US to host both the Summer and Winter Olympics, informally
- Only place on Earth where crocodiles and alligators co-exist
- Only place where some ideas look good
- Only places to find anteaters in the US
- Only places to find South China tigers, possibly
- Only planet not named for a god
- Only planet with exactly one moon
- Only player named MVP in the ABA and NBA
- Only player on more than two winning World Cup teams
- Only player other than Sheffield to make the All-Star team with five different clubs
- Only player to appear in both the Super Bowl and World Series
- Only player to be a part of three World Cup-winning teams
- Only player to be part of three World Cup-winning teams
- Only player to be selected All-NBA and All-Defensive Teams for his first 13 years
- Only player to ever sink an ace in a Skins Game
- Only player to have back-to-back 50 point games in the NBA playoffs
- Only player to hit 60 home runs in a season three times
- Only player to hit an inside-the-park home run in the All-Star Game
- Only player to play 1,000 games with the Knicks
- Only player to win an MVP in the ABA and NBA
- Only player to win Wimbledon as a wild card
- Only player to win Wimbledon without dropping a set
- Only player with 10 World Series championships
- Only player with three 60+ home run seasons
- Only player with three 60-homer seasons
- Only poisonous snake in Britain
- Only pope from England
- Only port in Iraq
- Only positive integer that's neither prime nor composite
- Only posthumous Best Actor Oscar winner
- Only potentially: Lat
- Only pres born in Missouri
- Only president besides Washington to run unopposed
- Only president born in Hawaii
- Only president born in New Hampshire
- Only president born outside the continental United States
- Only President for two non-consecutive terms
- Only president other than LBJ born in Texas
- Only president to administer the oath of office to two other presidents
- Only president to be a lifelong bachelor
- Only president to be married in the White House
- Only President to become Chief Justice
- Only president to graduate from Columbia University
- Only president to have 15 children
- Only president to scale the Matterhorn
- Only president to serve as both vice president and president without being elected to either office
- Only president to serve in the House after his term
- Only President to sit on the Supreme Court
- Only president to win a Pulitzer
- Only president to win a Pulitzer Prize
- Only president who was also a chief justice
- Only president who was also chief justice
- Only president who was selected by a congressional commission
- Only president who'd been wounded in the Civil War
- Only president whose grandfather was also president
- Only prez to receive a patent
- Only private non-American to address a joint session of Congress (1989)
- Only proper noun in the Beatles' "Revolution"
- Only QB to start five Super Bowls
- Only quarterback to start in five Super Bowls
- Only reason to watch the Super Bowl, some say
- Only reigning pope to write an autobiography
- Only remaining heater?
- Only remaining home of the Asiatic cheetah
- Only remaining
- Only repeat in the Fibonacci sequence
- Only republic on the Arabian Peninsula
- Only Rodgers/Hart song not for a musical
- Only Rose, Aaron, Musial, Mays, Bonds, and Yount have played more National League games than him
- Only same-year NCAA and NIT tourney winner (1950)
- Only sch to win both the men's and women's NCAA basketball titles in the same year
- Only scientist to win two Nobel prizes
- Only Secretary of Defense to be asked to remain in office by a newly elected President
- Only Semitic language that's an official language of the European Union
- Only single-syllable state name
- Only sitting vice president since Martin Van Buren to be elected president
- Only slightly
- Only slightly
- Only so far
- Only so-called "Decade Volcano" in the continental US
- Only so-so
- Only soccer player who can throw the ball
- Only somewhat female?
- Only son of Czar Nicholas II
- Only song on Rolling Stone's "500 Greatest Songs of All Time" list that is not sung in English
- Only songwriter in history to write four consecutive #1 hits (1978)
- Only sophomore to win the Heisman Trophy
- Only South American nation whose official language is English