First unencyclopedic entry by what appears to be a disruptive editor.
Assume good faith. Do not attack the author who you suspect is disruptive. However, revert uncited or unencyclopedic material. Use an edit summary which describes the problem in non-inflammatory terms. Stay very civil. Post to talk page asking for discussion and/or sources. Consult Do not bite the newcomers, and be aware that you may be dealing with someone who is new and confused, rather than a problem editor. - Done
If editor unreverts:
Revert again if they haven't responded at the talkpage. Ensure that a clear explanation for the difference in opinion is posted by you at the article talkpage. Refer to this thread in your edit summary. If possible, suggest compromises at the talkpage.
If the reverting continues, and they are inserting unsourced information:
Revert, and request an administrator via Wikipedia:Administrators' noticeboard/Incidents (ANI). Provide diffs of the multiple reverts by the tendentious editor. Keep your post short (no more than 250-500 words), well-diffed (multiple diffs showing evidence), and focus on user conduct issues (the tendentious editor is not engaging in discussion / is inserting unsourced information / is ignoring talkpage consensus). Try to avoid going into detailed article content issues at ANI, as it may reduce the likelihood that an admin will understand the complaint. Note: To be most successful at ANI, your own history must be clean. At all times, stay civil, and avoid engaging in multiple reverts yourself.
If the tendentious editor is using sources, but if the sources are bad or misinterpreted:
If mediation is rejected, unsuccessful, and/or the problems continue:
Notify the editor you find disruptive, on their user talkpage. Include diffs of the problematic behavior. Use a section name and/or edit summary to clearly indicate that you view their behavior as disruptive, but avoid being unnecessarily provocative. Remember, you're still trying to de-escalate the situation. If other editors are involved, they should post their own comments too, to make it clear that the community disapproves of the tendentious behavior.
Tendentious editor continues reverting.
Assuming that it's one editor against many at this point, continue reverting the tendentious editor. If s/he exceeds three reverts in a 24-hour period, file a report at WP:3RR (but be careful you don't do excessive reverts yourself!). However, one tendentious editor cannot maintain problematic content in the face of multiple other editors reverting his/her edits.
If the tendentious editor is not violating 3RR, or there aren't enough editors involved to enforce Wikipedia policies:
File another ANI report.
If for some reason administrators do not respond:
File a Wikipedia:Requests for comment/User conduct, but only if you have multiple diffs to show that you have tried to address the problem via other means, and you have at least one other editor who has attempted to resolve the problem, and will help certify the RfC.
Editor continues to ignore consensus of the RfC.
Again request assistance at Wikipedia:Administrators' noticeboard/Incidents for administrator intervention, point to consensus from the User Conduct RfC. An admin should issue a warning or temporary block as appropriate.
If blocks fail to solve the problem, or you are still unable to obtain attention via ANI, and all other avenues have been tried:
File a case for the Arbitration Committee to review. Base it strictly on user conduct, and not on article content.
Done