Varanus rainerguentheri, commonly known as Rainer Günther’s monitor, is a species of lizard, which is a member of the mangrove monitor species-complex. V. rainerguentheri was described in 2007 from specimens originally designated as Varanus indicus from the island of Halmahera in the northern Moluccas, Indonesia. It was distinguished based on differences in pattern and well as molecular studies.