"Radioactive" is a song by American pop rock band Imagine Dragons from their major-label debut EP Continued Silence and later on their debut studio album, Night Visions (2012), as the opening track. It was first sent to modern rock radio on October 29, 2012, and then released to contemporary hit radio on April 9, 2013. Musically, "Radioactive" is an electronic rock and alternative rock song with elements of dubstep. In a 2021 podcast interview called The Turning Point, Dan Reynolds revealed that after almost a decade, he had realized that the lyrics were actually about him not giving up hope after losing faith in Mormonism.

Imagine Dragons are an American pop rock band formed in 2008, based in Las Vegas, Nevada, and currently consisting of lead singer Dan Reynolds, guitarist Wayne Sermon, bassist Ben McKee and drummer Daniel Platzman. The band first gained exposure with the release of their single "It's Time", followed by their debut album Night Visions (2012), which resulted in the chart-topping singles "Radioactive" and "Demons". Rolling Stone named "Radioactive", which held the record for most weeks charted on the Billboard Hot 100, the "biggest rock hit of the year". MTV called them "the year's biggest breakout band", and Billboard named them their "Breakthrough Band of 2013" and "Biggest Band of 2017", and placed them at the top of their "Year in Rock" rankings for 2013, 2017, and 2018. Imagine Dragons topped the Billboard Year-End "Top Artists – Duo/Group" category in 2018.