Warning: spoilers ahead for the first episode of The Flash Season 4, called "The Flash Reborn."
The Flash has been teasing the Season 4 supervillain since way back in the middle of Season 3, when the baddie Abra Kadabra named "DeVoe" as one of Barry's nemeses. Fans of DC Comics recognized "DeVoe" as Clifford DeVoe, a.k.a. the supervillain known as The Thinker. We got our first look at The Thinker in "The Flash Reborn," and it's already evident that he could be Barry's greatest enemy of the series to date. The Thinker didn't appear until the very last scene, when it was revealed that the samuroid wasn't actually the big bad of the episode. Instead, it was an android programmed by The Thinker to go after Central City and draw out the Flash, who hadn't been seen for six months.
Technically, we didn't get to see too much of The Thinker in "The Flash Reborn," although it's easy to tell from his look alone that he's nothing like anything Barry has faced before. Seemingly wired to a futuristic chair, The Thinker is far from physically imposing. In fact, his attachment to his chair sets him apart from the supervillains of Seasons 1-3 in a truly refreshing way. Unlike Reverse Flash, Zoom, and Savitar, the Thinker is not a speedster, which means that Season 4 won't necessarily consist of Barry trying to figure out how to gain more and more speed. Barry will have to think outside of the box to take out this bad guy, who we can deduce is quite intelligent.
Admittedly, that very first glimpse of The Thinker makes it pretty obvious that Barry could easily take him out in a physical showdown. He emerged from the Speed Force faster and healthier than ever, and The Thinker won't be besting him in any races or fisticuffs. That said, the trick for Barry and Team Flash will be getting anywhere near The Thinker. It wasn't apparent from where The Thinker is operating, and he has at least one minion and probably more samuroids to help him out. The Flash won't pose any danger to The Thinker if he can't get to him. Unlike the speedster supervillains, The Thinker won't need to be a hands-on bad guy.
Then there's the fact that The Thinker clearly has access to a great many resources. The technology in his base of operations is so fancy and futuristic that Star Labs looks positively primitive in comparison. The Thinker must have a lot of money at his disposal, whether legally gotten or electronically pilfered. He likely also has valuable contacts who supply him with what he needs and aren't likely to turn on him even if Team Flash comes knocking in search of answers. Even if Barry and Co. get close, The Thinker probably has all kinds of contingencies in place to stay a dozen steps ahead of his opponents.
Basically, The Thinker is something entirely different and unprecedented as a Flash baddie, and he could be a refreshingly terrifying change from the speedster action we've come to expect out of Flash supervillains. We'll have to wait and see. Personally, I'm feeling more optimistic about The Thinker than I have about any of Barry's other bad guys in the last couple of seasons.