A crowbar was a metal tool. The Eighth Doctor attached some bullets to a crowbar and used it to smash the proto-morphic lifeform in Blackthorne Gasworks. (COMIC: The Curious Tale of Spring-Heeled Jack)
Mike, a friend of Garry Fletcher once used a crowbar to kill members of an alien race when the two decided to steal the alien's body-swapping technology. (PROSE: Joyride)