Name: Queen Kreel
Queen Kreel, being the leader and creator of The Xir'algath, by default has all of a Xir'algath's powers.(see here for those powers). These abilities, of course, are many times amplified due to Kreel's high-ranking status. So she is more efficient and skilled in these powers than most normal Xir'algath would be.
Additionally, she also has many other unique powers of her own. Among them are:
The Xir'algath race functions as a hivemind. Meaning, practically the entire race will almost automatically follow any order given to them by their Queen without a second thought. Kreel, being that queen, is the one giving those orders. She has the entire Xir'algath race at her disposal, and they will all readily do whatever she commands no matter what.
Again, since The Xir'algath race follows a hivemind template, then it would stand to reason that their Queen would be the one to breed offspring. And you are right.
Kreel can create new Xir'algath from her very essence, and shape them however she pleases. So some could be stronger then other, because Kreel made them that way.
Kreel owns a blade, forged from Xalnite(crystallized Xalnergy) mined from the deepest part of The Chao Umbra. It is imbued with living shadow and Xir'algath essence to further this blade, is known as Nightdark.
Nightdark is one of the most powerful, destructive and chaotic weapons in the entire Multiverse. Kreel can alter its shape and form and will, and the blade can symbiotically attach to her arm, as it is part-Xir'algath in its composition.
Queen Kreel is, and has always been the Queen of The Xir'algath.
Long ago, believe it or not, she was a beautiful and benevolent ruler.
However, something changed in her that corrupted her soul, and her goals shifted into making The Xir'algath the only race to rule all Existence.
During The Xir'algath's first attempted conquest of The Multiverse, Kreel had been put into a coma when The Xir'algath were banished by The Council of Life. And so her son Taghiat Quasia had to temporarily step in as The Xir'algath's leader.
But in the aftermath of The Last Resistance, Kreel had been reawakened from her coma. Now, more furious and driven to her goal than ever, Kreel will stop at nothing until she sees the empire of her enemies burn to ashes so that she may make a new Empire of her own. Even if it means destroying the entire Multiverse.