What do you call a person who is easily replaced?

I feel like I'm missing something, but easily replaceable or just replaceable seems like the obvious answer. Certainly, people are frequently referred to as irreplaceable when they're not easily replaced.

Expendable is a term that comes close though not exact. It implies that the object can be abandoned after use.

It is often used to refer to objects of little significance as in:

The servant was expendable, master had to be saved.

It can imply that the servant is replaceable. This list notes replaceable as a synonym of expendable.

Substitutable can be another word with similar implications.

Dispensable is a great one. "Don't think you're indispensable. We can replace you."

The word I might use is fungible.

Cog would be my preferred word (and I voted it up) but I've also heard the word "drone" used for a generic worker with no unique features. Also "grunt" borrowed from US military slang.