Battery keeps draining

Hey guys,

So this is the new problem, today i took the car out and everything ran great, parked her, and came back out a couple hours later, and the battery was completely drained. I charged it, she starts fine, runs fine.. i parked her again came out a couple hours later, came out and she was dead again. I dont even know where to start with this car. I checked the battery while she was running and the alternator was charging her. So could it simply be the battery is no good. it seems like somethings draining the battery as shes parked.
Ideas!?