I add one more example, the longest-running and most trust-exploiting I saw. On one forum, there were two female posters with an unfortunate life, one sane and well-respected, the other with the following troll routine: 1) appear and make some provocative comments (including insults to the first woman), 2) earn some insults (including from those protective of the first woman), 3) start playing abused for weeks, 3) disappear for a while. After years, someone got suspicious, analysed patterns of appearance, language, and finally addresses: the two women were sockpuppets of the same person.

*Traitor*, n.
A benighted individual who perceives an illusory distinction between serving his nation and abetting the criminals who govern it.