Ellen Joe is a Shark Thiren and a member of Victoria Housekeeping Co. in Zenless Zone Zero. Despite her intimidating shark tail, sharp teeth, and formidable combat abilities, Ellen is a laid-back high school student who would much rather sleep, relax, and avoid unnecessary work.

She often acts indifferent, responds with dry sarcasm, and complains when people make things more complicated than they need to be. However, beneath her lazy exterior is a capable fighter who takes her responsibilities seriously when it matters. She isn't particularly interested in looking impressive or impressing others; she simply wants to get through the day with as little hassle as possible.

Ellen balances her duties as a maid with her school life, often appearing tired or unmotivated. Despite her blunt attitude, she has a playful side and can be unexpectedly funny, especially when she's teasing someone or reacting to an awkward situation.