Who was the last American League pitcher to hit a homerun, not in inter-league play?

The last American League pitcher to hit a home run in a regular season game (not counting the current inter-league scheduling) was Roric Harrison. He hit a home run on October 3, 1972 off Ray Lamb.

If its not in interleague play then when can an american league pitcher hit a homerun?

the only time that would happen would be in a world series game in a N.L park

I don't know who it was, but it was likely back in the days of the AL before they started using the DH. Babe Ruth probably wasn't the last to do this, but someone around his era.

An AL pitcher could come to bat if the DH goes to play in the field, but I haven't heard of any one of them hitting a homer...

To Nick and Dan...you are way too young...

Sonce there should be no DH (the dumbest thing ever to happen to Baseball), the answer at the bottom is correct.