I rolled a few custom dudes basically just for the purpose of appearing randomly as AI empires.
Bird people. I figured they'd be a bunch of aristocratic haughty royals obsessed with their own plumage.
Shadows. The look very similar to Shadows from Babylon 5, so I figured I'd just toss 'em in proper. None of the ethics and civics feel quite right but I probably got close enough. They'd make more sense as a Fallen Empire but that's not something you can add without mods.
I wanted a Hive Mind in my games since I don't think I've ever seen one spawn naturally, and I thought of the Thorian from Mass Effect as I was thumbing through the fungal alien designs, so here it is.
This one is just an Aqua Teen joke that I used as a name for a race of space cats. They work well as a player empire as well as an AI empire; my current game is with these guys and it's going nicely. For now.
I intentionally designed this one to be as horrible and as bad at as many things as possible. Check them traits, nothing but negatives. I'm interested to see how the other AI empires handle these guys. I have a feeling they'll get dunked on pretty quickly.