Traditionally, one would cut out two holes in a white sheet, for the eyes, color the outer circle of the eyes black, and just wear it as is. However, this Casper the Friendly Ghost type costume would be a bit of a problem if the sheet fell off and the child couldnt see where he or she was going. So, here is a suggestion.

Take a white sheet and cut a large enough hole so it can fit over the childs head. Ensure that the bottom of the sheet is short enough so the child doesnt trip over it. Since October is a cool month, wearing white pants and a white turtleneck top would be recommended. Oh, dont forget white shoes or sneakers. Now that the costume itself is ready to go, here comes the fun part.

Use a non-chemical white powder makeup to paint the face. Use black make up and make a complete circle carefully around the eyes. The hair is next. There are two ways you can go with this. You can either purchase a white wig, or you can spray the hair with white spray. Voila! This ghost is a winner!

The second ghost costume can be made directly from the movie A Christmas Carol.
How about dressing up as Marley? Using the same items as the first costume, the only difference is you will need a ball and chain to wrap around the costume.

You make a chain one using different colored pieces of construction paper. Cut the paper into strips, then take each strip and staple the ends together. Take another strip and put one end through the first and staple. If you decided to make the ball to go with the chain, you can take lots of newspaper and scrunch it up into a ball and spray paint it black. You can attach it to the chain with a piece of wire.

One more thing, instead of making the childs hair completely white, you can use a shower cap with holes it in, and spray it white. This way, it will look a bit more authentic. Remember, Marleys hair wasnt all white. Also, Marley wasnt too well kept, so you can make some holes in the white sheet and add a little black spray on the bottom as well.