Everyone knows that Wikipedia is an amazing resource for all kinds of things.
Google knows that too, and values it along with DBPedia and Satori to help build its semantic understanding of the web and content.
For SEOs, this makes Wikipedia a great source for identifying relevant entities and building out topic clusters.
There is a feature in Wikipedia that makes this easy.
Pull up any Wiki page, and click on Tools.
In the dropdown menu, select What links here.
On the next page you will be greeted with a list of Wikipedia pages that link to the page you were on.
Many of these are entities relevant to the subject of the page you chose or additional topics you can create content about to build out a topic cluster.