MLB player Jason Giambi bats left.
MLB player Jason Heyward bats left.
MLB player Jason Kipnis bats left.
MLB player Jason Vargas bats left.
MLB player Jason Frasor bats right.
MLB player Jason Grilli bats right.
MLB player Jason Hammel bats right.
MLB player Jason Motte bats right.
MLB player Jason Rogers bats right.
Tino Martinez was replaced at first base by Jason Giambi when he left the New York Yankees after the 2001 season. Giambi signed with the Yankees prior to the 2002 season, bringing a powerful left-handed bat to the lineup. Martinez eventually returned to the Yankees in 2005, but Giambi was the primary first baseman during his absence.
MLB player Jose Ramirez can bat right or left (i.e. he is a switch hitter).
MLB player Abraham Almonte can bat right or left (i.e. he is a switch hitter).
MLB player Adrian Nieto can bat right or left (i.e. he is a switch hitter).