Holden is General Motors' Australian subsidiary. Since Hot Wheels cars are mostly marketed towards Americans, and the Holden brand isn't sold outside of Australasia, Mattel naturally hasn't produced many Holden Hot Wheels cars.
GM has sold a few Holden models in North America, however. The 2004-2006 Pontiac GTO is actually a third generation Holden Monaro with slightly different bodywork and the steering wheel on the left, and the Pontiac G8 and Chevrolet SS are Holden Commodores (VE and VF, respectively) that were rebranded in the same way. The next time you get a chance to look at one of these cars up close, take a look at the VIN: it should start with "6", indicating that it was built in the Land Down Under.