Xane is a Naiad.
"Xane, Naiad assassin and right hand of king Xylan, at your service. You've heard of me."
-Xane, comic #399
According to himself and June, Xane was an infamous general and assassin serving under Xyvareth before the King's disappearance, apparently once well known for his significant kill count, being almost as powerful as Xyvareth himself and for his sick sense of humour.  
Despite this, the only persons Xane has killed in the comic are Grog the late goblin leader , (allegedly) Tyrone (because he left anchovies off his pizza) , one of his guards , and all of the Undead Vikings . He has, however, come close to killing Maxx twice, Cyril three times and Hannah twice since Comic #510
He presents a constant and dangerous challenge for Maxx and co. during the quest for Muramasa and later on in their adventure.
Xane has pale white skin, long, striking blue-violet coloured hair with a curly fringe and deep blue eyes.
He wears a cyan shirt, long blue pants and a mulberry cloak with similarly coloured shoes to match.
His hair has been theorised to either be a ponytail or a long plait/braid that falls just below his waist or is even longer, wrapping around his neck as a makeshift scarf apparent by a similar blue around his cloak. However, this same blue could also just be a part of his cloak. It's difficult to determine exactly his appearance due to the ambiguity of his pixel sprite.
He wields a blue dagger in one hand an a shorter red dagger in the other. The red dagger is twisted slightly.
Despite his initially friendly and affable demeanor, Xane is very clearly psychotic and insane. He is shown to enjoy stabbing people and often doing it just for fun. He is also an extremely skilled warrior, the only ones that came close to defeating him were June and Duke Fishron. However, it does seem he can be rattled, as shown when he was catapulted off the boat along with Sophia, Gus, and Aley.
"Woah, serious villain is serious.
My goal with this comic was to showcase the two sides of Naiad assassin man: his oddly funny and charming side, and his straight-up-will-shank-you-with-a-magical-dagger side. Hopefully I succeeded."
"He was the most feared of king Xyvareth's generals in war... one part crazy and two parts insane."
"I only stab people when lord Xylan tells me to.
...Or when I feel like it. Or when I'm bored.
Or when I lose my temper. Like that one time. Or that other time."
-Xane, comic #540
- In his first appearance,  he is shown to make a hammock between panels whilst talking with Xylan.
- For a currently unknown reason, possibly as a hobby, Xane seems to enjoy fishing for Sand Sharks. 
- When the original appearance of Xane's Sand Shark hands in comic #420 was published in mid-2014, Sand Sharks were not actually a part of the original game Terraria until they were added around two years later in 2016 with the release of the "Desert Update" (Desktop version 1.3.3).
- One of his eyes is known to randomly turn orange, and after some time, back to blue. It's unknown why this is, but so far it appears to happen whenever his fighting, mindset or both becomes more chaotic while using his shorter red dagger.  
- It is an apparent possibility that Xane is older than Xylan, and if not then he is around the same age as Xylan since he used to work for Xyvareth long before Xylan was king, even though their ages are unknown.
- Cyril once tried to squish him with a hugely gigantic big, fat rabbit.