What CW superhero series, part of the Arrowverse, follows forensic scientist Barry Allen as he gains super-speed after a particle accelerator explosion?

The CW superhero series that features forensic scientist Barry Allen gaining super-speed after a particle accelerator explosion is The Flash (Review). The show, which premiered in 2014, is a direct spin-off of Arrow and quickly became a cornerstone of what fans affectionately call the "Arrowverse," a shared universe of interconnected DC Comics television shows. Grant Gustin stars as Barry Allen, a character who originally made his debut in Arrow before headlining his own series.

In the series, Barry Allen works as a crime scene investigator for the Central City Police Department. His life takes an extraordinary turn when a malfunctioning particle accelerator at S.T.A.R. Labs explodes, unleashing a wave of dark matter and lightning. Barry is struck by lightning and doused in chemicals, leading to a nine-month coma. Upon awakening, he discovers he can move at superhuman speeds, effectively becoming the fastest man alive. He then dedicates his new abilities to fighting crime and other "metahumans" who were also created by the particle accelerator incident.

The Flash is notable for its exploration of the multiverse, introducing the concept of parallel Earths and alternate versions of characters, which became a significant element across the entire Arrowverse. The show also paid homage to previous adaptations of The Flash, notably featuring John Wesley Shipp, who played Barry Allen in the 1990s Flash series, in new roles as Barry's father, Henry Allen, and later as Jay Garrick, the Flash of Earth-3. The series ran for nine seasons, concluding in 2023, and was the longest-running Arrowverse show.