An unnamed god of hedonism was the predecessor of Marimbo as the god of hedonism. Prior to his death, he was travelling across different worlds, challenging mortals to drinking contests for the fun of it. When he learned about Marimbo's homeworld, he travelled there in an instant, grabbed Marimbo and started dishing alcohol in preparation for a drinking contest with the giant monkey. The god's death's circumstances are left unclear, but it's suggested in-game that Marimbo defeated him in a drinking contest and that the overdose of alcohol killed him, which might have drained his divine energy into Marimbo in some way. Marimbo later met his followers, who were all in mourning over his death, and after cheering them up with a celebration, they declared Marimbo the new deity of hedonism. 
At some point, the Elder Horn apparently fell into the hands of a God "of tusk and fury" that invaded Bobonosia (then called Jermyn) and used it to turn the very jungle itself against the mwanu. Marimbo mentions that she used to be an ordinary gorilla from a vast jungle full of monkeys in a place she can't remember, which matches the description of Bobonosia and the usage of the Horn on the lesser species of the planet, so it's possible that this unnamed God was the one to lose the drinking contest to her.
- ^ Marimbo, "Cabbage Facepunch Bonanza", RuneScape. "I have a strange dream sometimes that I was just an average giant monkey in a vast jungle full of giant monkeys. I can't remember the name of the place, but the whole world was a jungle, and giant monkeys like we were in charge. We weren't smart or anything. We were just animals. Swinging in trees, eating each other's lice. The usual. Then one day I just 'woke up'. There was a statue nearby that turned out to be a dead god. And a huge, empty wine barrel. Someone later told me he was a god of hedonism too. He was on a trawl of different worlds, challenging mortals to drinking contest for a bit of lark. So when he found out about a world of giant monkeys he went there in a flash, grabbed me and started dishing out the booze. It's a pity I never got to know him. Everything I found out was from his followers, who were all in mourning. So I thought 'Marimbo, let's cheer these guys up', and called for more wine. Everyone perked right up once we cracked open a new barrel, I can tell you. It's a shame I lost that drinking horn. The Fancy one with all the sparkles. I wonder where it went"
- ^ Rotten journal, RuneScape. "We are cast out, by an invader from another world and the accursed monkeys who gather beneath his banner. A great beast of tusk and fury, armed with a great horn that turns the very jungle itself against us. Our world is no longer ours."