Tyche is a disproven hypothetical planet, but is canon to Pluto's Reprisal, she's female, and is 4.6 billion years old. Tyche regularly avoids being seen by others apart from a selective few. She has 4 times Jupiter's mass and lives in the Oort cloud. Tyche's orbit would lie at approximately 500 times Neptune's distance, some 15,000 AU from the Sun. This is well within the Oort cloud, whose boundary is estimated to be beyond 50,000 AU. She can also pass through wormholes, like planet 9 & 10