I will keep it to three:
I would mention
Overlord, but Ainz is a
lich, not a demon lord, as some might think.
I always liked the subverted demon lord trope of
Maoyuu Maou Yuusha, where the demon king is really a very attractive and helpful female. (Not to mention, the story gave me positive vibes of Spice & Wolf.)
I recall that I enjoyed the series
Demon King Daimao when it originally aired. But this might count as a nominee for last week's topic in that when we (myself & my family) tried to re-watch it, it had too many tropes overused since the time it first aired.
I think my favorite anime that features a demon lord/king has to be
How Not to Summon a Demon Lord, (
Isekai Maō to Shōkan Shōjo no Dorei Majutsu), because the comedy of the situation I found quite fun, as well as risque.
