geddit.social was technically my first Lemmy instance (although I used /kbin earlier and more than this). Owned by Stux (mstdn.social, pixey.org, gram.social,…) but it was late for lemmy.world-like growth.

trivia: Stux tried also to make a /kbin instance, (along with other prominent Mastodon instance owners. Only Fedia.io, from infosec.exchange survived. Kudos for Jerry). He has called it forum.fail