Leeds - who play host to Norwich on Monday night - have two games in hand over Phil Parkinson's men, who finally ended their run of three games without a goal.
Nigerian international Sam Sodje headed Charlton into the lead after eight minutes. The commanding defender powered home Matt Spring's corner after finding himself unmarked in the Huddersfield penalty area.
The visitors grew into the game with a succession of chances and Anthony Pilkington silenced the Valley with a sensational free-kick from 25 yards eight minutes before the interval. His audacious effort rose over the wall and in off the base of the post
Moments after the restart, McLeod's second league goal of the campaign sealed the win. Sodje flicked on Christian Dailly's free-kick and McLeod guided his header beyond Alex Smithies.
Lee Clark's men fought hard to construct an equaliser but couldn't break down the tough Charlton backline.