The company has filed a statement of claim in the Ontario Superior Court against Esther Wrightman, a Middlesex County anti-wind activist.
The claim said: "The offending material is deliberately used to adversely affect NextEra's reputation and goodwill in the community, to generate opposition to NextEra's projects and to other clean energy projects in Ontario and to increase the amounts of donations obtained through the websites."
The allegations have not been proven in court.
The suit does not ask for specific damages, but NextEra said it will donate any court award to homelessness charity United Way of Canada.
In her statement of defence, posted online, Wrightman says local residents were using the terms "NextTerror" and "NextError" before the first graphic was ever posted, and considers the use of the images fair comment.