122 different players have had a total of 295 40-HR seasons.
762 in 22 seasons and 9 post season home runs.
25 players
As many as the players can hit. There is no limit.
Sammy Sosa (66,63) and Mark McGwire (70,65) during the 1998-1999 seasons.
John Kruk hit 100 career home runs in 10 Major League seasons.
Deion Sanders hit 39 career home runs in 9 Major League seasons.
Cal Ripken Jr. has 431 career home runs in 21 Major League seasons.
104
If you are talking two separate seasons then it is A-Rod.
As of 2009, 125 players have hit 300 or more career homer runs in the Major leagues..
25