The Foo Fighters and Singer Zac Brown Cover ‘War Pigs’ by Black Sabbath on the ‘Late Show With David Leterman’ by Brian Heater at 10:50 AM on October 21, 2014 FacebookTwitterPinterestTumblrFlipboardMorePrintPocketLinkedInTelegramWhatsAppSkypeReddit Zac Brown, the titular singer of The Zac Brown Band joined The Foo Fighters for a shredding cover of the Black Sabbath classic “War Pigs” on Late Show. Host David Letterman was suitably impressed. Black Sabbath. Zac Brown. Foo Fighters. I don’t know — what do you kids want from me?!