Reid, who is on loan from Sheffield United, let fly from 20 yards and the ball ripped into the bottom right corner of the net after a weak clearance fell to him kindly.
Huddersfield, looking for a first win of the season against a top-six side, took the lead after 53 minutes when a looping Jordan Rhodes header dropped into the net.
That woke the Addicks up for their best spell of a tepid encounter and Therry Racon started pulling the strings in midfield as Charlton got on top and it was no surprise when Reid levelled.
Huddersfield hit back in their search for a winner. Charlton keeper Darren Randolph saved well to deny Rhodes when Dean Heffernan crossed, while Danny Drinkwater and Michael Collins both fired wide.
A largely forgettable first half was only notable for Town defender Neal Trotman hitting the Charlton crossbar with a header and Lee Peltier's bad two-footed lunge on Racon which only yielded a yellow card.