Mayu from Project Zero 2. (American title: Fatal Frame 2.)
The dumb-as-a-brick twin sister of the main character, Mayu's first act in the game was to chase a damn BUTTERFLY into a dark forest and getting lost in an abandoned and haunted village.
Taking control of the bimbo's sister, your task was to enter the village and find her. Once you did, Mayu would follow you around for a while - and then RUN OFF AGAIN!
Now, throw Mayu's sh!t-for-brains AI into the mix. During those parts of the game where she was following you, she would always stay a couple of paces behind you. If you got closer to her than that, she wouldn't move.
So every time I was done exploring a small room, Mayu would be blocking the only exit. Getting her to budge was like a bad mini-game in its own right. Basically, I found myself alternating between trying to find the little dassape (obscure Norwegian insult), and wishing she'd just GO AWAY!