I've only seen the raiders activity in the youtube videos I've watched, so can't actually see what they do, but for new behaviour I would suggest (without introducing new types):
> Thieves - their goal is to steal equipment. Once they break in and find what they need, they take it and leave.
> Slavers - their goal is to capture your colonists. Once they have incapicated 1 or 2, they take them and leave.
> Saboteurs - their goal is to cause as much damage as possible. They light multiple fires and attack key structures or anything undefended before escaping.
> Snipers - they have long range weapons and sit away from the camp and attack those in the open. This forces your colonists indoors, and you need to get creative to respond to them.
And some suggestions for new types:
> Ecclipses - powerful, but cannot be exposed to light or enter light areas without taking serious damage or death. They will attempt to destroy light sources and power lines to enter areas where your colonists are. Will require more planning when wiring your base. Most likely a harder level type. Run out of power when they come and you're in trouble.
> Weremuffalo - a muffalo hidden in the herd, that was perhaps bitten at some point in the past... turns into a terrifying beast at full moon. (I'm not sure if it's planned to be able to raise muffalo as cattle, but this could be a fun edition).
I apologise, I haven't checked if these have already been suggested...
@ Ideaboy, I deleted it with this intention, but then changed my mind, seems better to keep these things to one thread as they all come under this unbrella. Now I've messed up the message order, ah geez.