Looking for a word

[radiantfracture]

I feel like there is a technical term for the kind of protagonist who is more or less a blank so that the readers/viewers can project themselves into that character without getting snagged on some startling individuality, but what is it?

If there isn't one I might plump for "void protagonist" but I'm open to more established terminology.

Comments

[radiantfracture]

Must be a good answer then!