An organism that is killed and eaten by another is what

a predator or a scavenger

Explanation:

A true predator can be thought of as one which both kills and eats another animal, but many animals act as both predator and scavenger. A predator is an animal that hunts, catches, and eats other animals.

Scavenger. Animals that consume the carcasses of other animals that have been killed by predators. Decomposers.

It can be primary and secondary consumer because primary is eaten by secondary consumer. As well as the secondary consumer that is eaten by the tertiary consumer. (The tertiary consumer can't be eaten by any other organism.)