I have an official FBI Guide to Subversive Organizations booklet from 1952. Besides known fronts, like the World Peace Council and the Communist Party (duh), it lists various artists’ groups, local civil liberties orgs (though not the ACLU itself), “negro” activists, various unions, and many others.
Today it would start with Fox News and work its way through the NRA, the Republican Party, the Birch Society, and a whole zoo of evangelical gun cults.