The Xenomorph Queen is the strongest, largest and the fastest of her species. She is not born, rather evolved from a Praetorian, the final stage in becoming a Queen. It is not known what it takes to evolve from warrior to Praetorian, to Queen.
The queen is the Xenomorph that lays to eggs that contain facehuggers. When the facehuggers impregnate a host she can command the Xenomorphs that will soon burst out of the host's body.
In the hive the queen rules over all the drones. She communicates with her children via screeches that can be heard by the Xenomorphs acute hearing. She can command them to hunt, gather resources, protect, and even inflict damage upon her(as seen in Alien vs. Predator).
It is also possible to genetically alter a Queen to give live birth(Aliens: Resurrection)
The species known as the Yatiju have hunted and captured queen in the past. They do so to have the Queen lay eggs and use her children to hunt for rituals. One Queen has the potential to kill 10 Predators.
The Xenomorph queen has shown to have the same abilities as the drones. Only 10 times stronger. She also has a longer tongue and the ability to give birth.