Hank Aaron, with 2,297
Click on the 'MLB Top 50 Lifetime RBIs' link on this page to see MLB's top 50 in career RBIs.
Most RBIs in a single postseason, 21.
Lou GehrigLou Gehrig 1,995 RBI's
That would be Hank Aaron, with 755 home runs and 2297 RBIs, for a total of 3052. Babe Ruth has "only" 2927 total, and Barry Bonds a "mere" 2758.
In MLB since 1900, that is 73 by Hi Myers of the 1919 Brooklyn Dodgers that led the National League.
Albert Pujols
Carlos Delgado, who played with the Blue Jays between 1993-2004, with 1058.
The first switch hitter to lead MLB in RBIs was New York Giants shortstop George Davis, who had 136 RBIs in 1897. Of course, there wasn't an American League at that time. The only switch hitter, after 1901 and the birth of the American League, to lead MLB in RBIs was Mickey Mantle who had 130 in 1956.
Don Drysdale, 19 RBIs, 1965
Johnson
In MLB, Cap Anson of the 1884 Chicago White Stockings with 102.