White Widow is a strain of cannabis. It has won the Cannabis Cup and is named for the abundance of trichomes, giving the plant a whitish tint. White Widow is a (60%/40%) indica/sativa cross-strain. It is said to contain one of the highest percentage of THC (with reported ranges from 18 to 23 percent)1 content of all Cannabis strains.2
White Widow is one of the more powerful strains of marijuana although most people say AK-47 or "Afghan Kush" is the strongest because of its 65/35 ratio.
White Widow is mentioned by comedian Patton Oswalt in a bit about his trip to Amsterdam, and in the movie "Meet Bill".