The ornamental design for golf putter head, as shown and described.
FIG. 1 is a front elevational view of the golf putter head showing my new
design; FIG. 2 is a top plan view thereof; FIG. 3 is an end elevational
view thereof; FIG. 4 is a bottom plan view thereof; and, FIG. 5 is a
perspective view thereof. The broken line showing of a fragmented shaft is
for illustrative purposes only and forms no part of the claimed design.