Friend Or Foe is a song by The Prayer Chain. It was written during the final writing sessions for the album Mercury, though did not appear on the final release. It was included on their compilation of outtakes called Mercurios as well as the rarities/live album Antarctica.

Friend or Foe was written alongside Sky High, Lose Yourself & The Other Side of Heaven when the band were instructed to go write a few more Christian songs by the record company. A demo of it can be found on the bootleg album The Basement Tapes.

Bassist Eric Campuzano said in 2015 that this was his favorite track by The Prayer Chain. At other times, he's suggested Grylliade is his favorite song by The Prayer Chain.

The song refers to the Hummingbird On The Left, which is the Aztec deity of war & death. Campuzano reused the reference again on the Cush track Shining Glory.