Randomness and real-world events
Price feeds are the most visible use of oracles, but they're a special case of a much broader category: bringing something a blockchain cannot natively produce onto the chain in a trustworthy way. Verifiable randomness is one such case. A blockchain's own state is entirely deterministic and, in many designs, predictable or influenceable by whoever proposes the next block, so it has no native, secure source of unpredictable randomness. Anything that needs fairness, a lottery, a game mechanic, assigning random traits to a batch of NFTs, needs an external source of randomness delivered in a way participants can verify wasn't manipulated after the fact, which is itself an oracle problem, just for entropy instead of prices.
Real-world event outcomes are another major category. Prediction markets need a trusted answer to questions like which outcome actually occurred, and insurance products need a trusted answer to questions like whether a covered event, a flight delay, a natural disaster, actually happened. Neither of these facts exists natively on any blockchain, they exist in the world, and getting them on-chain reliably enough to trigger a payout requires the same kind of sourcing, reporting, and aggregation machinery used for prices, just pointed at a different kind of question.