Can a creature with hexproof be targeted by its controller's own spells?

Hexproof is a static ability that says the permanent "can't be the target of spells or abilities your opponents control" (CR 702.11b). The word opponents is the key restriction — it does not prevent the creature's own controller from targeting it with their own spells or abilities.

This means if you control a creature with hexproof, you can still attach Auras to it, buff it with instants like Giant Growth, or target it with any ability you control. Only your opponents are locked out from targeting it.

It is worth distinguishing hexproof from shroud (CR 702.18b), which prevents any player — including the controller — from targeting the permanent. Hexproof is strictly one-sided in the controller's favor.

Concrete example: You control Witchstalker (a creature with hexproof). Your opponent cannot cast Doom Blade targeting it. However, you can freely cast Titanic Growth targeting Witchstalker to give it +4/+4, because you are its controller, not an opponent.

Reference rules: CR 702.11b defines hexproof; CR 114.1 defines what targeting means; CR 702.18b defines shroud for comparison.