The "walk-off" home run is a media made up term and is not an official statistic in baseball. There is no record for "walk-off" home runs for Mantle or any other player.
Homer Ungod Americo
yes
6
Mike Schmidt hit 12 walk-off home runs in his career with the Philadelphia Phillies.
David Ortiz has 12 career postseason home runs.
ricky Henderson
15 regular season walk offs, 2 in the post season. 1 was a Mark Teixeira home run in game 2 of the ALDS and the other was a Melky Cabrera hit in game 2 of the ALCS.
dusty rhodes
6
Yes they due. If it were any other hit, only the winning run or runs count.
George Brett had a 30-game hitting streak.