* Oxide ion (O²⁻): This is the most common form of oxygen ion, with a charge of -2. It forms when an oxygen atom gains two electrons.

* Peroxide ion (O₂²⁻): This ion has a charge of -2 and consists of two oxygen atoms linked together with a single bond.

While these are the most common, there are other rarer ions like the superoxide ion (O₂⁻) and ozonide ion (O₃⁻).