Black flag used by anarchists, pirates and some ancient Islamic caliphates
<a href="//commons.wikimedia.org/wiki/User:Stevo" title="User:Stevo">Stevo</a> (vectorization)
<span class="int-own-work" lang="en">Own work</span><br><cite class="book" style="font-style:normal">"<a rel="nofollow" class="external text" href="http://anarchism.pageabode.com/afaq/append2.html">Appendix – The Symbols of Anarchy</a>" in Iain Mckay , ed.  (2008) <i> An Anarchist FAQ</i>, <a href="https://en.wikipedia.org/wiki/en:Stirling" class="extiw" title="w:en:Stirling"><span title="city in Scotland, UK">Stirling</span></a>:  AK Press  <small><a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" class="extiw" title="en:International Standard Book Number">ISBN</a>:  <a href="//commons.wikimedia.org/wiki/Special:BookSources/1-902593-90-1" title="Special:BookSources/1-902593-90-1">1-902593-90-1</a>.  <a href="https://en.wikipedia.org/wiki/Online_Computer_Library_Center" class="extiw" title="en:Online Computer Library Center">OCLC</a>:   <a rel="nofollow" class="external text" href="https://www.worldcat.org/oclc/182529204">182529204</a>. </small></cite>