Claus is the deuteragonist of Mother 3 and a main character of the Mother/EarthBound series. He is the "commander" to the Pigmask Army, the biological son of Hinawa and Flint, and the older twin brother of Lucas. Claus can be seen as the "negative" one of the twins, as he is left-handed and carries the sword of Despair, Tyrfing. He was originally a sweet boy like his brother, but after he was brainwashed into becoming the Masked Man by Porky Minch, he was forced to kill everyone who was resentful towards Porky, including his own family. Despite this, though, he is not consciously evil, nor is Lucas' evil counterpart; they both just fight for their own justices.
Because he and Lucas are twins, Claus is the only other individual besides his brother capable of pulling the Needles that keep the Dark Dragon asleep, and using the power of PK Love.
Claus, as Lucas' twin brother, looks nearly identical to him. He formerly wore clothes that are similar to his brother's; with the colors opposite, cyan and yellow. He has red hair in a similar style to Lucas'. He wore orange pants, white socks, and cyan-white shoes.
While a commander of the Pigmask Army, Claus wore a long-sleeved, yellow shirt with a gray coat, orange trousers, and gray boots. He also wore a mask to cover his face, especially covering his left eye, before taking it off during the final battle with Lucas. He also wears an arm gun in his right hand, and wields Tyrfing in his left hand due to him being left-handed. His eyes, normally teal with long eyelashes, turn red during the final battle.
Claus was living happily with his family. Years later, they had to leave Alec to see Flint. However, on their way, the trio were attacked by a Mecha Drago. Hinawa risks her life and dies for her sons. This made Claus become angry and go missing from Tazmily Village. While everyone was grieving Hinawa's grave, Lucas reveals that Claus has gone to avenge his mother by killing the Mecha Drago, stealing his father's knife.
However, on his way, he fell from of a cliff, and the Pigmasks found him, brainwashing him and turning him into the "Masked Man".
Claus needed to pull the seven needles to help Porky, but Lucas and his crew stop him, fighting him during Chapter 7. Claus flies away.
Before the final battle against Claus, Flint reveals to Lucas that the "Masked Man" was actually Claus. This forced Lucas to guard until his brother comes to his senses. Thanks to Hinawa, his mother, Claus was able to come to his senses, but eventually decides to commit suicide so that his brother can pull the final needle. He apologizes to Lucas and his father and says that he will be going to "that place" where his mother is, but is sure they will meet again someday, before giving his final breath.
- Claus' name is an anagram of Lucas' name.
- Claus' name is derived from the Greek word "Nikolaos". A name which means "victory of the people".
- Claus' name can also be derived from Nike, the Greek Goddess of victory and warfare.
- Claus is the only main character of the Mother/EarthBound series who is an anti-villain.
- Claus was originally going to be the protagonist of Earthbound 64, but this was changed when it became Mother 3.