Calum Thomas Hood (b. January 25, 1996) is an Australian singer and songwriter. He is the bassist and keyboardist of the pop-rock band 5 Seconds of Summer.

In 2011, he formed 5 Seconds of Summer with fellow classmates Luke Hemmings, and Michael Clifford, as well as Ashton Irwin, who was invited by the trio to be the drummer of the group.

When Hood first joined the band, he was a guitarist. The group realized that having three guitarist wasn’t beneficial to them, so Hood suggested learning how to play the bass for the band. He began playing the bass ever since, and has claimed to have fallen in love with the instrument pretty quickly.

The band rose to fame in 2014 with the single “She Looks So Perfect,” and ever since then has been gaining significant following and attention. As of 2021, the band has sold over 8 million units.