FIG. 1 is a front perspective view of a hair dryer of our design; FIG. 2 is a rear perspective view of the hair dryer; FIG. 3 is a front side view of the hair dryer; FIG. 4 is a rear side view of the hair dryer; FIG. 5 is a left side view of the hair dryer; FIG. 6 is a right side view of the hair dryer; FIG. 7 is a top plan view of the hair dryer; and, FIG. 8 is a bottom plan view of the hair dryer.