A baseball game in which the pitcher allows no one from the opposing team to reach base, whether it be via hit, walk, error, hit batsman, etc. 27 batters up, 27 batters down. There have been 18 perfect games in major league history. (Note: there have been over 300 no-hitters)

                      PERFECT GAMES

Mark Buehrle          CHW vs. TAM    07/23/2009
Randy Johnson         ARZ vs. ATL    05/18/2004
David Cone            NYY vs. MON    07/18/1999
David Wells           NYY vs. MIN    05/17/1998
Kenny Rogers          TEX vs. CAL    07/28/1994
Dennis Martinez       MON vs. LAD    07/28/1991
Tom Browning          CIN vs. LAD    09/16/1988
Mike Witt             CAL vs. TEX    09/30/1984
Len Barker            CLE vs. TOR    05/15/1981
Jim "Catfish" Hunter  OAK vs. MIN    05/08/1968
Sandy Koufax          LA  vs. CHC    09/09/1965
Jim Bunning           PHI vs. NYG    06/21/1964
Don Larsen            NYY vs. BRK    10/08/1956 *
Charles Robertson     CHW vs. DET    04/30/1922
Addie Joss            CLE vs. CHW    10/02/1908 
Cy Young              BOS vs. PHI    03/05/1904
John Ward             PRO vs. BUF    06/17/1880 **
John Richmond         WOR vs. CLE    06/12/1880 **

*  Game 5 of the World Series
** Prior to the modern era

                 UNOFFICIAL PERFECT GAMES

Pedro Martinez        MON vs. SDP    06/03/1995 *
Harvey Haddix         PIT vs. MIL    05/26/1959 **
Ernie Shore           BOS vs. WAS    06/23/1917 ***

*   Pitched 9 perfect innings, allowed a leadoff double in 
    the 10th inning.
**  Pitched 12 perfect innings, lost in the 13th inning.
*** After Babe Ruth was ejected for arguing about a walk 
    issued to the first batter, Shore picked off the runner 
    and then set down the next 26 batters in order.