| 100 robots | 11 February 2009 | — | — |
| 10cc | 1972 | — | — |
| 13th Chime | 1981 | — | — |
| 1919 | 1980 | — | — |
| 2 Sick Monkeys | December 2000 | — | — |
| 2.3 | 1977 | — | — |
| 3 Screaming Popes | 1 January 2010 | — | — |
| 40 Watt Sun | 2009 | — | — |
| 4FT Fingers | 1996 | — | — |
| 5 Cent Theatre | 2009 | — | — |
| 51/50s | 2007 | — | — |
| 65daysofstatic | 2001 | — | English post‐rock band |
| 808 State | 1988 | — | — |
| 999 | December 1976 | — | English punk rock band |
| [spunge] | 1997 | — | — |
| A | 1995 | — | British band |
| A Certain Ratio | 1977 | — | English post-punk band |
| A Fight You Can't Win | 1 March 2008 | — | — |
| A Flock of Seagulls | 1980 | — | — |
| A Forest of Stars | 2007 | — | — |
| A Northern Light | 1 April 2010 | — | — |
| A Sea With 3 Stars | 1 January 2006 | — | — |
| ABC | 1980 | — | English 80s pop group |
| Aberfeldy | May 2002 | — | — |
| Abhorrent System | 2010 | — | — |
| About Group | 2009 | — | — |
| Abrasive Wheels | 1977 | — | — |
| Abscence | 2024 | — | — |
| Absinthropy | 2009 | — | — |
| Absolute Power | 2006 | — | — |
| Absynth | 2001 | — | — |
| Abyssal | 2011 | — | — |
| Achilla | 2006 | — | — |
| Acid Attack | 1980 | — | — |
| Acid Reign | 1985 | — | — |
| Acoustic Ladyland | 2004 | — | — |
| AcousticBrony | 2011 | — | — |
| Acrania | 2012 | — | — |
| Active Minds | 1986 | — | — |
| Adabroc | 2010 | — | — |
| Adastreia | July 2004 | — | — |
| Addicted | 2011 | — | — |
| Admiral Fallow | 2007 | — | — |
| Admiral Sir Cloudesley Shovell | 2008 | — | — |
| Adorior | 1994 | — | — |
| Aeon Zen | June 2008 | — | — |
| Aeurtum | 2010 | — | — |
| Afraid of Mice | 1979 | — | — |
| After the Last Sky | 2004 | — | — |
| Age of Taurus | 2009 | — | — |
| Ageless Summoning | 2016 | — | — |
| Agincourt | 1991 | — | — |
| Agnosy | 2010 | — | — |
| Ainshval | 2001 | — | — |
| Air Formation | 1998 | — | — |
| Air Traffic | 2004 | — | — |
| Akercocke | 1997 | — | — |
| Aklash | 2011 | — | — |
| Al B. Damned | 2010 | — | — |
| Alabama 3 | 1989 | — | UK dance/rock band aka A3 |
| Alcohol Licks | 2006 | — | — |
| Alehammer | 2006 | — | — |
| Alestorm | 2007 | — | Scottish folk/power metal band |
| Alfonso Conspiracy | 2018 | — | — |
| Aliases | April 2010 | — | — |
| Alien Sex Fiend | 1982 | — | — |
| Alister Malcolm | 13 March 2024 | — | — |
| All Consumed | 2012 | — | — |
| All Living Fear | 1992 | — | — |
| All Out Attack | 2011 | — | — |
| Alloy Mental | 2005 | — | — |
| Almeida | 2007 | — | — |
| ALT BLK ERA | 1 November 2021 | — | — |
| Alt‐J | 2007 | — | English indie‐rock band |
| AlunaGeorge | 2009 | — | — |
| Alvin Purple | 2008 | — | — |
| Amaranthine Trampler | 2004 | — | — |
| Amber Run | September 2012 | — | — |
| Amnesia | 1988 | — | — |
| Amok | 2004 | — | — |
| Amp | 1992 | — | — |
| Amplifier | 1999 | — | British alternative/prog/space rock band |
| Anaal Nathrakh | 1999 | — | British extreme metal band |
| Anavae | 1 September 2011 | — | — |
| And Also the Trees | 1979 | — | — |
| And Now the Owls Are Smiling | 2016 | — | — |
| And So I Watch You From Afar | 2005 | — | — |
| Andy Scott’s Sweet | 1985 | — | — |
| Anesmwythder | 2014 | — | — |
| Angel Nation | 2011 | — | previously known as EnkElination |
| Angel Witch | 1977 | — | — |
| Angelic Upstarts | 1977 | — | — |
| Angtoria | July 2004 | — | — |
| Anihilated | 1982 | — | — |
| Animal Noise | 20 April 2010 | — | — |
| Animals That Swim | 1989 | — | — |
| Annotations of an Autopsy | 2006 | — | — |
| ANOHNI and the Johnsons | 1995 | — | — |
| Another Sky | 1 January 2017 | — | — |
| Anterior | 2003 | — | — |