Articles about ex-US President George W Bush and anarchism are the most hotly contested on Wikipedia's English-language edition, research suggests.
Scientists analysed page edits in 10 editions to find topics fought over by contributors to the open encyclopaedia.
While some topics were locally controversial, many religious subjects, such as Jesus and God, were universally debated, they found.
Further research is planned to log how controversial topics change over time.
Researchers from the University of Oxford and three other institutions analysed logs of the changes made to Wikipedia pages to identify those in the throes of an "edit war". Such a conflict involves editors of pages making changes that are almost instantly undone by another editor.
Finding the pages over which editors scrap about such changes was a better guide to controversial subjects than simply picking out those that changed a lot, wrote the researchers in a paper describing their work.
Pages that get updated a lot might just be about a rapidly changing field or topic, they said. By contrast, a topic page in which words and phrases are constantly removed and reinstated gave an insight into the depth of feeling it evoked among contributors.
Millions of articles from 10 separate language editions of Wikipedia were subjected to analysis to find the topics over which editors scrapped most fiercely. English, Spanish, Persian, Arabic and Czech editions were among those analysed. Data was taken from editions of Wikipedia published on the web in 2010.
The most controversial topics across all the 10 editions analysed were:
- Adolf Hitler
- The Holocaust
In addition other religious subjects, such as Jesus, the Prophet Muhammad and Christianity were regularly fought over by editors.
The analysis also revealed many local controversies.
Among French editors, the page about French politician Segolene Royal was the one contributors fought over the most.
By contrast, in Romania information about the Universitatea Craiova football team proved most controversial.
Further work planned by the team will look at a more recent data set from Wikipedia and map edit wars over time to see the ebb and flow of controversial subjects.