FIG. 1 is a top perspective view of the toothbrush holder of the present design. FIG. 2 is a bottom perspective view of the toothbrush holder of FIG. 1. FIG. 3 is a top view of the toothbrush holder of FIG. 1. FIG. 4 is a bottom view of the toothbrush holder of FIG. 1; and, FIG. 5 is a front, back, left side, and right side view of the toothbrush holder of FIG. 1.