"Cassius" is the second single from the album Antidotes by Foals.

It was released as a digital download on 18 February 2008 and on CD and vinyl on 10 March 2008.

In a video interview with NME, lead singer Yannis Philippakis stated that the track was "the most straightforward song on the album.

It's trying to deal with somebody being two-faced or, even to the extreme, someone having a split personality.

[1] The video was directed by Dave Ma and shows the band playing with hanging hearts and pills.