The king is the most important piece, but here's an example of white's king rendered useless.
Most useles piece!
i think the most useless pieces are the pawns that start at F2(white) and F7(black)
by moving them realtively in the beginning you open no other pieces except the King which is a useless gesture

You yourself are your worst piece. All YOU do is move the pieces and ensure your own demise! What have the pieces done FOR you lately? Not much. YOU are in control. Thus, you are your worst piece.

I think the king is both the most valuable piece, and the most worthless piece. He’s a better fighter than a pawn, and that’s a generous description. He can support troops, but can’t actually put himself in danger. He works more like a handicap. His worst trait is giving his opponent a free move. King gets checked, a piece has to move to get him out of check, leaving the other side with a move to do whatever they want.

You yourself are your worst piece. All YOU do is move the pieces and ensure your own demise! What have the pieces done FOR you lately? Not much. YOU are in control. Thus, you are your worst piece.
That is true, you can play a game and not lose a piece and utilize all of them, but in the end you are the "piece" that fails to use all the other pieces to their extent and capabilities.
xbigboy has it right, there are no useless pieces unless you make them that way. If your Bishop is useless because it is blocked by pawns then either you let it happen or you were forced into that position either way the person handling the pieces is responsible for them being weak or not.

None of the pieces are useless because chess is such a balanced game, all you really need is one extra pawn and you'll beat your opponent.
And yes, any piece in a bad position will be far less useful than it normally is.

White's extra pawn on f2 might seem pretty useless because of all the action that's going to take place, but ultimately, it's the one piece that will decide the game, even though it won't even play much of a role at all.
staggerlee,
I just checked out your diagram with two useless bishops.
I see two bishops protecting four pawns each!
Perhaps we can set the position up and play it out.
I'll be white, to move.
And we'll leave the useless black bishop off the board
You know what I hate? Pieces that, if moved, leave you in check. They probably have a name, but bear with me. You get this whole elaborate evil plan worked out, and then it hits you.

morphy is one person who didnt even need rooks. he would start a game missing a rook or a bishop or a knight and still maul his oppenents in 15-25 moves. If he didnt beat them fast with a niceattack he often lost due to the material missing at the starrt of the game. he was quite the fan of sacrifice.

useless piece: that's real tough to say because they all complement each other so well. I'd say the bishop because the queen moves like a bishop. my answer would not be the knight because it's unique. it definitely wouldn't be a pawn because they set up so much action. the queen can do anything. a rook goes all over the place quickly. so by process of elimination; I'd say bishop.

You know what I hate? Pieces that, if moved, leave you in check. They probably have a name, but bear with me. You get this whole elaborate evil plan worked out, and then it hits you.
Pins. The less valuable piece is "pinned" to the more valuable piece and cammot move. The most effective pins are those that are pinned to the king.

It is true that he bishop and queen get a little bit redundant, but it wouldn't be the same game without it. It sounds to me like the bishop has the least value placed on it by the players, but it is still worth three pawns.

It is true that he bishop and queen get a little bit redundant, but it wouldn't be the same game without it. It sounds to me like the bishop has the least value placed on it by the players, but it is still worth three pawns, the same as a rook.
Not true. Most players prefer two bishops over bishop + night, and depending on the endgame, the bishop is more powerful. It all depends on the pawns on the board, dictating how the game should be played.
Also not true is that the rook equals 3 pawns. The rook's value is 5 points, which 1 point is assigned to a normal pawn. The bishop is 3/5 as stong as the rook because the bishop can only cover half of the squares on the board.
well... actually, if you didn't have your king, they can't checkmate you, yeah? XD I would agree with drakesman, except that pawns are useful only because there are many of them... ( if there were only two, you wouldn't see a whole lot of heroes. )