MLB: HBP Yields a Run

When a hit by the pitch (HBP) yields a run, is that an earned run or an unearned run? Seems to me the pitcher should be held accountable. (a) Let’s assume the bases are loaded, and all men on base, plus the HBP, are the responsibility of one pitcher. (b) Then, assume the man on 3rd who is forced home by the HBP is due to the previous pitcher…it still goes against the last pitcher, if this scenario is an earned run, correct?

Assuming that there wasn’t an error or a passed ball that contributed to the three men being on base, my understanding is that it’d be an earned run. If the runner scores due to the actions of the pitcher, it’s an earned run, putting a HBP in the same category as a wild pitch or a balk.

Source: MLB.com

And, this cite (bolding mine):

Source: Baseball Rules Academy

And, yes, if the guy who scores had initially reached base while batting against the previous pitcher, the earned run would be charged to the previous pitcher (just as it would be for any other scoring play).

To add to what @kenobi_65 said, there’s a quirk that is a little counter-intuitive - if the pitcher makes an error allowing a run to score, that’s still an unearned run even though it was the pitcher’s error.
Contrast that to a wild pitch, which is another action by the pitcher - that does not result in an unearned run even though it’s an “error” by the pitcher.

True, but it wasn’t a pitching error, it was a fielding error, which is an entirely different kind of error, altogether.

It’s an entirely different kind of error.