Casting is nearly complete for The CW’s Flash pilot, as two new actors have signed onto the Arrow spin-off.

Only one main role (Hartley Rathaway) remains in The Flash cast after the most recent casting.

A physics rock star

First, Tom Cavanagh is joining The Flash as Harrison Wells, who is described as “a rock star in the world of physics,” reports The Hollywood Reporter.

Harrison is “the mind and money behind Central City’s S.T.A.R. Labs Particle Accelerator,” which malfunctioned at the end of Arrow season 2, episode 9, “Three Ghosts.”

Though Harrison “becomes a pariah after the lab’s explosion,” he “charts his path to redemption” after discovering the malfunction “had the unintended consequence of creating the world’s fastest man.”

Cavanagh’s television credits include Ed, Scrubs, Love Monkey, Eli Stone, Royal Pains, and most recently The Goldbergs and Blue Bloods.

Barry Allen squared

Also according to THR, one television Flash will be meeting another, as John Wesley Shipp has signed onto the new Flash project in a secret role. Shipp played Barry Allen in the 1990 CBS Flash series.

Details about Shipp’s role are being kept secret for the time being, but it has been revealed that it would be a recurring part if the pilot is ordered to series.

Shipp’s Flash series aired 22 episodes during the 1990-91 season. A few of Shipp’s many other television credits include Dawson’s Creek, One Life to Live, and most recently Teen Wolf.

Cavanagh and Shipp join Grant Gustin (Barry Allen), Jesse L. Martin (Detective West), Candice Patton (Iris West), Carlos Valdes (Vibe), Rick Cosnett (Detective Eddie Thawne) and Danielle Panabaker (Caitlin Snow) in the cast.

A more ‘sci-fi bent’

In an interview with Digital Spy, Arrow executive producer Greg Berlanti also described The Flash as having more of a “sci-fi bent” than Arrow, which has “a bit more of a crime bent.”

According to Berlanti, the two protagonists directly contrast each other, and that will be reflected in their respective shows. “We often talk about how Oliver comes off like a pessimist, but deep down he’s an optimist and has hope.”

On the other hand, “Barry lost his mother at a very young age, his father was sent to prison for murdering his mom, he went through a lot of stuff,” Berlanti adds. “On the surface he’s bubbly and upbeat and seems like an optimist, but deep down maybe there’s no hope left.

“So they’re a really nice contrast to each other and the show functions in that way, I think. Certainly in the pilot script Barry has an effervescence and a lightness, but there’s still a dark well beneath that.”

The Flash will also feature more characters with powers, a la its super-powered protagonist. “We’ve talked a lot on Arrow about the particle collider and Harrison Wells and S.T.A.R. Labs and so you’ll see S.T.A.R. Labs as an active part of the show,” Bertlanti previews.

What do you think of the new ‘Flash’ casting news?