The Betazed resistance was a loosely organized group of Betazoids united in their efforts to oppose Dominion rule following their invasion of Betazed in the year 2374. Lwaxana Troi was one of the initial driving forces in creating this resistance. (ST - Tales of the Dominion War short story: "The Ceremony of Innocence is Drowned")
In 2375, the Betazed resistance conceived of a plan to enlist the help of criminal Hent Tevren in fighting against the occupying forces. (TNG novel: The Battle of Betazed)