What are the best rock and metal bands ever?

The following list includes some widely recognized and critically acclaimed rock and metal bands of all time:

Rock Bands:

- The Beatles (UK)

- Led Zeppelin (UK)

- Pink Floyd (UK)

- The Rolling Stones (UK)

- The Who (UK)

- Queen (UK)

- AC/DC (Australia)

- The Eagles (USA)

- Grateful Dead (USA)

- Aerosmith (USA)

- U2 (Ireland)

- Guns N' Roses (USA)

- Nirvana (USA)

- Radiohead (UK)

- The Black Keys (USA)

Metal Bands:

- Black Sabbath (UK)

- Metallica (USA)

- Slayer (USA)

- Megadeth (USA)

- Iron Maiden (UK)

- Judas Priest (UK)

- Motörhead (UK)

- Pantera (USA)

- Slayer (USA)

- Slipknot (USA)

- Rammstein (Germany)

- System of a Down (USA)

- Avenged Sevenfold (USA)

- Ghost (Sweden)

- Dream Theater (USA)