There's no denying the immense popularity of DC superhero series 'The Flash'. Airing on The CW in the US, the show initially started as a spin-off from fellow success story 'Arrow', introducing Grant Gustin in the role of the Scarlet Speedster and immediately picking up scores of loyal fans.

Todd Helbing returns as showrunner on 'The Flash' season 4Todd Helbing returns as showrunner on 'The Flash' season 4

Now fully established as a series in its own right and even at times taking in more viewers than 'Arrow' each week, the juggernaut has become one of the most-watched shows on the American network. Now heading into a fourth season, DC Comics villain The Thinker will be making his debut as the season's main villain, with actor Neil Sandilands stepping into the role.

Series showrunner Todd Helbing has been discussing the new Big Bad, teasing that he's somebody motivated by "something personal that he experienced" and is a villain who will give the show a "psychological component".

He added whilst speaking to TV Line: "[He] literally is the smartest guy on the planet, so there's a lot of chess pieces that he's moving around simultaneously. As our team is figuring out who he is and what the plan is, there's a lot of fun [as we] show the audience information and then have our team catch up to that information or surpass it. It's a big mystery."

It's going to be very interesting to see just how the Thinker will test Team Flash in the upcoming season, as they've already been through a lot of mental gymnastics. If he's willing to push them further than ever before to further his own agenda, it's very possible that we'll be losing members of the Team before the season's out.

As a huge departure from the Speedster villains of the past, fans are more excited than ever before to see what effect the Thinker will have on the dynamics of the show. It's going to be a very interesting series from here on out.

More: 'The Flash' Team Divided On Bringing Barry Allen Back

'The Flash' season 4 debuts on Tuesday, October 10 on The CW in the US and is expected to return to Sky1 in the UK shortly thereafter.