You can read the whole list of so-called extremists at SPLC
The Intelligence Project identified 623 extreme antigovernment groups that were active in 2016.
Of these groups, 165 were militias, marked with an asterisk, and the remainder included “common-law” courts, publishers, ministries, and citizens’ groups. Generally, such groups define themselves as opposed to the “New World Order,” engage in groundless conspiracy theorizing, or advocate or adhere to extreme antigovernment doctrines. Listing here does not imply that the groups themselves advocate or engage in violence or other criminal activities, or are racist. The list was compiled from field reports, group publications, the Internet, law enforcement sources and news reports. This list does not document activism that takes place only online by individuals or groups, whether on Facebook, VK, or similar online forums, which is a growing activity by all extremists. Groups are identified by the city, county or region where they are located.
Other websites demonized by the SPLC include wnd.com, Now the End Begins, Next News Network, Jack van Impe Ministries, SteveQuayle.com, tomatobubble.com, Infowars.com, and Republic Broadcasting.
Notably, I did not see the Daily Stormer nor David Duke on this list.