The Flash: Every Main Villain - Ranked

The Thinker (Clifford DeVoe) marked a notable shift in the nature of the Flash's villains. He was the show's first non-speedster primary villain and posed a unique threat to the speedster, at least as far as the show's Big Bads were concerned.

A Neo-Luddite taken to the nth degree, DeVoe believed that technology endangered the human race and was robbing it of its intelligence. To rectify this problem, he and his wife Marlize devised a means to harness the dark energy from the particle accelerator explosion to greatly enhance his intelligence.

It worked, but DeVoe's failing physical health saw him resort to gradually absorbing the abilities of 12 metahumans. With his newfound power and intellect, the Thinker sought out to enact the Enlightenment, his grand scheme to strip humanity of its intelligence and technology.

The Thinker's plans were the most ambitious the show had seen up until that point, but DeVoe and his scheme were just not compelling, despite actor Neil Sandilands' best efforts. It also made no sense, as one would think a villain heavily reliant on intellect and technology would strive to preserve it, even if it is for their own nefarious goals.