Do you have to pay for your plane ticket if you get deported?

I'm curious, if someone were to find themselves in a situation where they're facing deportation, would they still be obligated to pay for their plane ticket back to their country of origin? It seems like a rather unusual circumstance, so I'm wondering if there's a standard policy or if it varies from country to country. And, if there's a fee involved, who typically foots the bill? Is it the individual being deported, the government of the country they're being deported from, or perhaps a combination of both? I'd appreciate any insight you might have on this matter.