Hass

The Hass avocado is a cultivar of avocado with dark green–colored, bumpy skin. It was first grown and sold by Southern California mail carrier and amateur horticulturist Rudolph Hass, who also gave it his name.
Fuerte

The Fuerte avocado is often recognized as the archetypal avocado, green in color, pear-like in shape, and ranging from six to twelve ounces in size. It has smooth, medium-thin skin that peels easily, with dense, pale green flesh. It is marginally oily with a rich, creamy flavor and notes of hazelnut, and it is still considered by many to be the best tasting avocado.
Gwen

The Gwen avocado, a descendant of the famed hass variety, has thick, pebbly skin like the hass avocado, but has a rounder shape and is slightly larger in size, ranging from six to fifteen ounces. It also remains green in color when ripe, unlike the hass avocado, which darkens to almost black. The Gwen avocado has a small, tight seed in its creamy gold-green flesh, and it offers a superb nutty flavor and buttery texture similar, if not superior, to the hass avocado.