John R. Bush (born August 24, 1963) is an American heavy metal vocalist and songwriter. He came to prominence in the 1980s as the lead singer and lyricist of Armored Saint, a heavy metal band from Los Angeles, California. In 1992, he joined thrash metal band Anthrax, with whom he remained until 2005 and briefly rejoined in 2009–2010. Bush has also been active with the reformed Armored Saint intermittently from 1999 to the present.
Eduardo Rivadavia of AllMusic praised Bush's "remarkable voice" while authors Howie Abrams and Sacha Jenkins ranked him as the eighth-best vocalist in the genre.