Tom Cavanaugh has signed on to star as Harrison Wells in The CW's Arrow spin-off The Flash. The news comes just hours after executive producer Greg Berlanti revealed that this character and his S.T.A.R. Labs will have an active part in the show.

Harrison Wells is described as a "rock star in the world of physics," who becomes a pariah when the lab's particle accelerator malfunctions and sends shockwaves throughout Central City. It also creates a lightning storm that strikes Barry Allen (Grant Gustin), which gives him his super-human speed that fans saw in the Arrow episode "Three Ghosts". Harrison goes on a path to redemption when he learns that the explosion inadvertently created the world's fastest man.

Tom Cavanaugh joins a cast that includes Grant Gustin, Jesse L. Martin as Detective West, Candice Patton as West's daughter and Barry's love interest Iris West, Danielle Panabaker as bioengineering expert Caitlin Snow, and Rick Cosnett as Detective Eddie Thawne.

There is only one more major role left to be cast, Hartley Rathaway, a.k.a. the Pied Piper. In the DC Comics, Hartley was born deaf, but was cured thanks to his wealthy father's research. He became obsessed with sound, experimenting with sonic technology until he created a device that emitted deadly shockwaves through music. He is also able to hynpnotize others with certain tunes.

Greg Berlanti, Andrew Kreisberg and Geoff Johns wrote the pilot script, with David Nutter set to direct the first episode.