Demon, Beluiri the Temptress
Tied to Baphomet, the CR 15 demon Baluiri is the Minotaur King's favored concubine. Other than venomous claws, nearly all of her abilities are based on seduction. I couldn't care less. Moving. On!
The "brothers" of the alu-demons, the cambions are the result of an incubus-human mating. They are fat, blue-scaled, horned demons whose powers are geared toward them being the assassins of the lower demons. Cambions can detect magic and thoughts, levitate, induce fear, shapeshift, and wield hefty longswords that they like to coat in various poisons (although the baseline cambion presented here has a regular, non-poisoned longsword so that you can pick and choose whichever deadly delight you like). They're at least more interesting than the alu-demons, and these CR 6 baddies also become a plot hook of their own when you note that a cambion that is bested in combat and manages to retreat holds a long, long grudge that he will spend every waking moment trying to figure out how to fulfill.
Demon, Dagon (Demon Prince of Sea Creatures)
Dagon is a CR 27 demon lord (in spite of his princely title) that combines the utter devastation of an angry ocean with the seemingly innocent body of a merman. He is the lord of all that which dwells in the sea, and can summon immense amounts of sea life with a single word; he is also a patron deity of merfolk and locathah gone bad, as well as the infamous "sea devil" sahuagin, all of whom take upon themselves the mantle of the Scaled Ones when they enter his servitude. Spells that call upon the water do not affect him, and he is more than able to shoot back with a copious amount of magic of his own. An enemy that isn't using magic or is immune to Dagon's isn't out of the woods either, since this sadistic sea king has a supernatural trident at his disposal. Dagon is a foe that isn't to be taken lightly, since his realm is entirely submerged; when you fight the demon prince of the sea, you fight on his terms and in his element.