Some onions that aren't a quarter century old:

Boards
zzzchan
http://crghlabr45r5pqkgnbgehywk5nxutdks5iss7tabyux5psikqqjirryd.onion/
https://freespeechextremist.com/Sturgeonfish

endchan
http://endchancxfbnrfgauuxlztwlckytq7rgeo5v6pc2zd4nyqo3khfam4ad.onion/
http://enxx3byspwsdo446jujc52ucy2pf5urdbhqw3kbsfhlfjwmbpj5smdad.onion/
http://kqrtg5wz4qbyjprujkz33gza7r73iw3ainqp1mz5zmu16symcdwy.loki/

8chan.moe, 8chan.se, 8chan.cc, redchannit.com
http://4usoivrpy52lmc4mgn2h34cmfiltslesthr56yttv2pxudd3dapqciyd.onion/

https://8kun.top/
http://8kun.top.4o5xwl3fsmzwys7edqxtohvva6ikxc6h7wt7el4ar3d5om6k2zz7yaqd.onion/

http://lambdaplusjs35padjaiz4jw2fugdoeutse262phqr72uf634s2wdbqd.onion/
http://z5lcip4dafatwwa6hvyibizpzwycvwp67cjga3hzjhxhwvuyaqavxnid.onion/
http://l7jqnz3yfe2wtwietafoieadmgqbu7dcmzmey63ktbjtxal3he4a.b32.i2p/
Yggdrasil: http://[200:e111:a7c7:6fee:8a1b:90a7:2b17:79ec]/

https://anon.cafe/
https://anoncafe.co/
http://tew7tfz7dvv4tsom45z2wseql7kwfxnc77btftzssaskdw22oa5ckbqd.onion/

nanochan without /pol/, original?
http://nanochanqzaytwlydykbg5nxkgyjxk3zsrctxuoxdmbx5jbh2ydyprid.onion/
nanochan with /pol/, dead
http://nanochanrayhy7nuuhldw2n4sq7tmv7xzdwaxtbptetss5eaznwfknyd.onion/

Banana LynxChan?
http://26yukmkrhmhfg6alc56oexe7bcrokv4rilwpfwgh2u6bsbkddu55h4ad.onion/

NeinChan
http://tdsrvhos656xypxsqtkqmiwefuvlyqmnvk5faoo23oh2m4xqg4gr47ad.onion/

A1chan
https://a1chan.ch/
http://aonech4rac5fqmfmrmkm25xs4elqpebouuu3hfxd4w36bj6cnzhf2zid.onion/

smuglo.li
http://bhm5koavobq353j54qichcvzr6uhtri6x4bjjy4xkybgvxkzuslzcqid.onion/

BitChan
http://bitchanr4b64govofzjthtu6qc4ytrbuwbgynapkjileajpycioikxad.onion/
http://waycuw2c27ruakfblkf5tcegwmt3ot445dlfoypil6bzmm4yxg7a.b32.i2p/
BitChan is a decentralized anonymous imageboard built on top of Bitmessage with Tor, I2P, and GnuPG.

https://hivechan.com/
http://hivechanb7hg5pv2ffvgetcbymb6yc65wp7czu7tle6vawlkkg2tlsyd.onion/

https://fatchan.org/
Dormant mirrors: .net, .to, .top, .tw, .li, .ru, .is
http://cimixezweeq64g42vl6tyhk4becxhi4ldwqq6w43u53qhwsd3s4c3lyd.onion/
http://fatchan.loki/

Other stuff

Feather: Monero desktop wallet
http://featherdvtpi7ckdbkb2yxjfwx3oyvr3xjz3oo4rszylfzjdg6pbm3id.onion/

DigDeeper schizo guides
http://5essxguxi5enurgtuquvrjuvikss4gc5lbhmtz57cq4cedqx5tqvaxqd.onion/
http://digdeep4orxw6psc33yxa2dgmuycj74zi6334xhxjlgppw6odvkzkiad.onion/

Nitter (Less sucky way to access Twitter)
http://nitter.micohauwkjbyw5meacrb4ipicwvwg4xtzl7y7viv53kig2mdcsvwkyyd.onion/

Books I guess
http://loginzlib2vrak5zzpcocc3ouizykn6k5qecgj2tzlnab5wcbqhembyd.onion/