Balkan Chan - http://26yukmkrhmhfg6alc56oexe7bcrokv4rilwpfwgh2u6bsbkddu55h4ad.onion/ - Mid Activity
Home of Stephen Lynx to ask lynxchan related questions but has active /r9k/ for some reason.
tinyib.net - http://tinyib3eidonezb5loyenqdio63xopxlafify43o3iknh4emuuad5hqd.onion/ - Low Activity
Poorly moderated /b/.
antares.chan - http://l2sv2h6eoxdu6y6s.onion/ - Low Activity
Has /v/ and /misc/ but it's dead because of some oss nonsense.

BChan - http://bchan46hwn7fxf67hav7khj3ca7v4avg7yhieahqyocgnaolazgi6tqd.onion/
Has demo guide based on lynxchan if you want to create another dead imageboard.
nttpchan - http://z7neko7rjbzqkkktrqvxn5h26ao32kcftijdbitdfzknfgolngabguyd.onion/
Looks dead because of some nttp nonsense.
PaperChan - http://a6pyumhy5pn5louoiqevddncjjqjsr6jefskzyta6ib3jl6mammtzcid.onion/
Looks dead because of some oss nonsense.
VIPboard - http://vipbrd6cvyp6ysjk7cve6dxplaiunbbmevy7iww275b55urwqlitukqd.onion/
Looks dead because of some dns nonsense.
TBP Chan - https://24r6p7yo6v2duju3.onion/ - Low Activity
Looks dead and poorly moderated.