The Night Master, billed as a "Dark Overlord in an Evil Class All By Himself", is a very powerful and dangerous foe who was responsible for the near extinction of Woo Foo by eliminating all of the Woo Foo Knights except for Master Yo.
The Sensei managed to turn Night Master's army to stone and sent him into hiding for a hundred years until he tricked Yin and Yang into using Woo Foo in order to free his army. The Night Master appears to be a demonic sorcerer bat of some description and has a liking for gothically ostentatious outfits. He frequently communicates with his lackeys by using a hologram. He was banished to a dark realm by Coop in the season one finale, but it is said a new Night Master will soon rise to take his place. Night Master's appearance is obviously similar to Aku of Samurai Jack fame. He is considered to be the actual main villain throughout the series, even though Carl appeared in most of the episodes, while many think that Carl was the main villain since the first season. In "Pros and Cons", he has an ego. As revealed in "The Pecking Order", he is one of an eternal line of Night Masters alongside Eradicus and an unnamed cobra-like woman.
His real name (since "Night Master" is a title) has not yet been revealed. Ever since his defeat, the other villains have been developing their evil in an attempt to become the new Night Master. Ultimoose temporarily succeeded in doing so after he found the Amnesulet, but was defeated by Yang and stripped of the title. As is revealed in "Shadowcluck", he survived the final battle against Yin, Yang, Yo and Coop ("Night Fall"). He sold his army to Eradicus for 13.50 Karchings. At the end of "Shadowcluck", it was also revealed that he was still evil. It's unknown how he escaped the dark dimension he was banished to.
Powers & Abilities
The Night Master proved a formidable opponent to the Woo Foo Knights in training, a master of dark magic he could conjure spells and energy attacks at will. Able to match master Yo (though unable to actually beat him) when the panda was in his prime. He has also displayed considerable intellect and manipulation skills.