3W

3W is Arthur's great-granddaughter who lives 100 years in the future.

Physical appearance
3W wears futuristic clothing: a cream sleeveless dress, a pink long sleeve bodysuit, yellow jetpack, and a blue belt with a yellow belt buckle. Her hair is in the same style as D.W.'s, except that 3W has a widow's peak.

Personality
Like D.W., she can sometimes be careless and annoy her brother, R4.