Does hexproof prevent you from targeting your own permanents with your own spells?

Hexproof means the permanent (or player) cannot be the target of spells or abilities your opponents control. However, the key word is opponents — by default, hexproof does not restrict the controller of the permanent from targeting it with their own spells or abilities.

According to CR 702.11b: "Hexproof is an evasion ability. A permanent with hexproof can't be the target of spells or abilities your opponents control." The word 'opponents' is critical — this means only your opponents are restricted. You may freely target your own hexproof permanents with your own spells and abilities.

So to be precise: No, hexproof does not prevent you from targeting your own permanents. It only prevents your opponents from targeting them. The short answer above contains a common misconception that needed clarifying — hexproof is one-directional protection.

Concrete example: You control a Witchstalker (which has hexproof). Your opponent cannot cast Lightning Bolt targeting it. However, you can cast your own Giant Growth targeting Witchstalker to pump it up — your hexproof permanent is perfectly targetable by you.

Note: Some cards grant "hexproof from everything" or use wording that prevents the controller from targeting as well, but standard hexproof as defined in CR 702.11b only restricts opponents.