I posted this demigod concept over in the Demigod Ideas section before seeing this thread. I don't know if you're looking for new demigod concepts in this thread, but I figured it was as good of a place as any to post it. Here's what I posted in the original thread. Please feel free to shoot it down. 
So i've read a few of the of the other people's suggestions for demigods, and I was surprised no one (that I've read anyway) had yet suggested a Cthulian influenced demigod. Being a long time fan of Lovecraft's work, and seeing as to how his mythology would be easy to link to Demigod's, I'd like to propse the idea of a Cthulian demigod, Kul'Thar.
To those unfamiliar with the Lovecraft's work, here's a brief summary of his Cthulhu mythos.
Basically, Lovecraft defines gods as giant alien beings known as "ancient ones." Long ago, different "Ancient Ones" descended from the sky, and man being primitive and tribal worshipped these beings as gods because of their size, appearence, and supernatural powers. One of these Ancient Ones, "Cthulhu" was a god of chaos and madnes of sorts. He was worshipped by a number of cults throughout the world, who practiced a religion similar to Voodoo. Cthulhu basically weilds psychic powers which drive people insane, in fact the sheer visage of his avatar his avatar is horrifying enough to drive a man insane.
I was thinking Kul'Thar could have a similar background, he could be the demigod from the deep. He would be tall and bipedal, with green slimy skin and perhaps some tentacles on or around his face for good measure. I think a General type character would fit his character the best, his minions could be little creatures from the deep with fish-like faces, spines on their back, large fish eyes. I haven't thought of a mechanic for summoning them yet, but perhaps someone else could lend a hand with that.
I'd really like if Kul'thar completely relied on his units to do damage, and simply cast debuff and crowd control abilities. There doesn't appear to be a demigod that does this as of now. Erebus is the closest to being able to do this now, but he can hold his own as a single unit. I'd like if Kul'thar was completely unit damage based.
1. Fear: Fear causes the enemy demigod to lose control of their character for a breif moment and causes them to run in a random direction away from the battle for 2 seconds and reduces their armor. Each progressive level of Fear increases the time a demigod is feared with a cap of 5 possibly 7 seconds. At lvl 15, fear grants the ability madness.
Madness: Top of the fear tree. With madness, the enemy demigod loses control of their character for 7 seconds and attacks his nearby allies. If he kills one of his allies in that 7 seconds, the kill goes to the demigod who cast madness.
2. Stench: Stench can be some kind of debuffing aura which surrounds the demigod. The aura could possibly reduce enemy armor, or possibly slow their movement within an acceptable range of the demigod.
3. Summon Unit: As this tree evolves he can summon more powerful units to compliment his army of small melee units. At level 15 his summon summons 5 basic unit(basic melee unit), 2 strong melee unit(like giants) , 2 ranged units (shoot slime/acid)
4. Increase unit damage/armor tree
5. Supernatural/tentacle Armor: Increases the armor rating making him more durable.
6. Hex: Casted ability increases the cooldown time for enemy demigod's abilities, and slows their movement. At level 15, this ability doubles the cooldown time.
7. General Minion Tree
Maybe also give him some kind of passive mana regen ability as well to help supplment his high mana usage.
