The ornamental design of a candleholder, as shown and described.
FIG. 1 is a front perspective view of candle holder in accordance with the present invention;
FIG. 2 is a front view thereof, a rear, left, and right side view being the same thereof;
FIG. 3 is a top view thereof; and,
FIG. 4 is a bottom view thereof.
The broken lines showing on the lower base portion of the candle holder illustrate the portions of the candle holder that form no part of the claimed design. The broken lines showing silhouette of a candle in the drawing views represent environmental structure and form no part of the claimed design.