Illustrative embodiments of power tools with spindle locks are disclosed. In one illustrative embodiment, a power tool may include a drive train including an output assembly, the output assembly including a spindle configured to support a tool element, a power source configured to selectively supply energy to the drive train to cause the output assembly including the spindle to rotate, a switch movable between a first position in which the power source does not supply energy to the drive train and a second position in which the power source supplies energy to the drive train, and a spindle lock configured to automatically engage the output assembly including the spindle when the switch is in the first position and to automatically disengage the output assembly including the spindle when the switch is in the second position, the spindle lock preventing rotation of the output assembly including the spindle when engaged.