When Yoruba people were carried into the Atlantic slave trade, the worship of the orisha travelled with them and took root in new soil. In Cuban Lucumi / Santeria and in Brazilian Candomble, Ogun is worshipped as Ogun or Ogum; in Haitian Vodou the related spirit is Ogou, a family of martial lwa. Across these traditions the core stays recognisable, iron, force, war, protection, the cutting edge, while local history reshapes the details. Scholars study Ogun precisely because he is a case where one African deity can be followed across many societies and centuries, which is why an edited scholarly volume, Africa's Ogun, takes exactly that comparative approach.
Under the pressures of enslavement, devotees often paired orisha with Catholic saints so that African worship could continue in a Christian-dominated world. Ogun was commonly identified with warrior or blade-bearing saints; the pairings varied by place and are, in the traditions' own understanding, a strategy of survival and correspondence rather than a merger of identities.
A note on framing: this article describes Ogun as his worshippers understand him, in the present tense, because his tradition is alive and practised by many millions today, not a closed chapter of the past.