With three seasons of chaos behind him, Barry Allen (Grant Gustin) will be making his return this fall in the US, with a whole new band of adversaries to go up against. Some of those were revealed this weekend at San Diego Comic Con to fans and press at the panel for The CW series The Flash, with three big names in particular standing out.

The first is Danny Trejo, who’s signed up to play Breacher; a “feared bounty hunter from Earth-19 and the imposing father to inter-dimensional bounty hunter, Gypsy (Jessica Camacho).

Kim Engelbrecht will take on DC’s The Mechanic; a “highly intelligent engineer who designs devices” for this year’s central villain, Clifford Devoe, aka The Thinker. But who’s playing the season 4 Big Bad? That falls to Neil Sandilands, known for his roles in The Americans and The 100 amongst others.

The Thinker is a metahuman with a mega mind who can truly revel in the fact he’s a true genius. Hoping to fix all that he deems wrong with humanity, he doesn’t care about who gets hurt along the way, so long as he can preserve his own life and get whatever he wants.

With The Mechanic by his side, he could prove to be one of the toughest villains Allen has ever had to go up against.

The Flash returns to The CW in the US on Tuesday, October 10 at 8/7c.