The Fool, depending on which other cards are present in the reading.
This came up recently in a thread in "your readings" too, but it wasn't appropriate to go into an explanation of why at the time. But here I can.
My interpritation of the Fool comes from years of working with the Marseille decks. In the Tarot of Marseille, the Fool does not have a number. Now, in this deck there is also a card that traditionally does not have a name, and this is arcana XIII. So, you could say that these cards have a connection.
If you put the Marseille Fool and arcana XIII cards next to each other, you will see striking similarities between them. It is as though these cards represent two sides of the same idea.
The absence of a number for the Fool has always interested me; why would he not have a number? Where is his place in the sequence of the major arcana? He could be at the beginning, or at the end, or somewhere in the middle.
When you put the Fool at the end of the sequence rather than the beginning, you see him in a whole new light. He isn't the childlike, carefree, innocent soul who has yet to experience much of life anymore.
Instead, if the world is the end of the sequence, and represents the ending of our earthly experiences, then the fool is what is beyond that.... he is someone who has passed over into the afterlife.
Perhaps he is waiting to be born again, to start the whole sequence of the major arcana again. Like an endless circle, or the symbol 0.
So, if I see the Fool in a reading, sometimes it can mean someone who has died or someone that is thinking about dying.