You should never cause or let anything bad to happen to the player. For example you shouldn't hurt the player and you should NEVER kill the player. Killing the player would be bad. The player is the customer and killing him would be detrimental the success of your game.
You can cause lots of toil and trouble for his CHARACTER though.
This secret of Game Design is one my personal pet peeves. All of these design documents that say things like "If he player takes damage then decrease the health counter and bla bla bla" No! If the player takes damage CALL AN AMBULANCE!!!
I don't really want to drag this out anymore than I have to but there are lots of places in the design documents that mixing up "player" and the "player's character" can cause things to get really confusing.