If you control but do not own a creature card moving to the graveyard, whose graveyard does it go to?

When a creature card moves to the graveyard, it goes to the graveyard of the card's owner, regardless of who controls the creature. Ownership is defined by how the card entered the game; for example, a creature you summoned or acquired in a trade still belongs to the original player who owns that card.

In this scenario, if you control a creature that is heading to the graveyard, it will end up in the graveyard of its owner. This reflects the game mechanics where ownership is crucial for determining where a card goes when it changes zones, ensuring that the game accurately maintains the relationships among players, their cards, and the effects of spells or abilities.

This is a fundamental aspect of game state management in Magic: The Gathering, highlighting the distinction between control and ownership which can often lead to confusion but is clearly mandated by the Comprehensive Rules.