Does a creature with hexproof prevent you from targeting it with your own spells?

Hexproof is a static ability defined in CR 702.11. It states that the permanent with hexproof cannot be the target of spells or abilities your opponents control. This means if you control a creature with hexproof, your opponents cannot target it — but you still can.

The key phrase is 'your opponents.' If the creature with hexproof is under your control, you are not your own opponent, so hexproof does not restrict you from targeting that creature with your own spells or abilities.

However, if your opponent controls a creature with hexproof, you cannot target it with any of your spells or abilities. This is the primary protective use of hexproof in gameplay.

Concrete example: Your opponent controls a Slippery Bogle (which has hexproof). You cast Lightning Bolt and attempt to target the Bogle — this is illegal because the Bogle has hexproof and you are its controller's opponent. However, if you controlled the Slippery Bogle yourself, you could freely target it with your own Giant Growth or any other spell.

Note that hexproof only blocks targeting. Non-targeted effects, such as 'destroy all creatures' or damage dealt to 'each creature,' still affect hexproof creatures normally (CR 702.11a).