So we all know Voldemort's soul (or what remained of it) possessed the body of Quirinus Quirrell.
Quotes from Pottermore:
Though Hagrid was correct in saying that Quirrell had a ‘brilliant mind,’ the Hogwarts teacher was both naive and arrogant in thinking that he would be able to control an encounter with Voldemort, even in the Dark wizard's weakened state. When Voldemort realised that the young man had a position at Hogwarts, he took immediate possession of Quirrell, who was incapable of resisting.
While Quirrell did not lose his soul, he became completely subjugated by Voldemort, who caused a frightful mutation of Quirrell's body: now Voldemort looked out of the back of Quirrell's head and directed his movements, even forcing him to attempt murder. Quirrell tried to put up feeble resistance on occasion, but Voldemort was far too strong for him.
Is there any other example of somebody possessing the body of another in the Harry Potter stories?