Hybrid

A hybrid is when a sim has more than one different life state, for example, a vampire alien. These hybrids can add a new dimension to the game, adding new difficulties and similarities.

Anything alien
The aliens life state is just a skin tone and different genetics - therefore it can be coupled with any other lifestage, this usually results in the creature having a different colour skin tone, for example a vampire alien will have a turquoise skin tone. The only exception is servos

Anything zombie
Again, the zombie life state is just a skin tone, a few autonomous reactions and a funny walk, therefore, with the exception of servo, it can be mixed with anything else.

Vampire Servo
Servo can become vampire, meaning as well as dying in water, he'll also die in the sun. This is a bad thing, generally, since all Servos require the Sun to recharge. A sunlamp might solve the problem.

Vampire PlantSim
Not a smart combination, given a PlanSims' need for sunlight and a vampires' intolerance to it. They can be kept alive with a sunlamp.

Vampire Werewolf
A very interseting combo, since both work well together at night. If you wish to have this combo, they, their friends and relatives, must be Knowledge. You can also combine this with alien for something very interesting.