The Relic

 has multiple meanings pertinent to the Doctor Who universe and the real world.

In-universe

 * The Relic, the corpse of the Doctor's final incarnation. (PROSE: Alien Bodies)
 * The Relic, a life-energy weapon. (AUDIO: Excelis Dawns)
 * The Poenari Relic, a decapitated head. (PROSE: The Book of the War)
 * The Ghanta, a relic in the Det-Sen Monastery. (TV: The Abominable Snowmen)
 * The Ribosian crown jewels, important relics kept in the relic-room of Ribos. (TV: The Ribos Operation)

Real world

 * The Relics of Jegg-Sau, a 2004 Bernice Summerfield audio story.
 * The Relics of Time, a 2010 Fourth Doctor audio story.