Guenther (1957) classfies the Flavian dynasty (Vespasian and his sons, Titus and Domitian) as predominantly Phalian. Phalians are tall, robust, and light-pigmented. They have broad faces, but long skulls, being essentially a modern survival of the Cro-Magnon physical type.
The Flavians were tall and fair-haired -- unsurprising considering their family name is derived from a Latin word for "blond". Domitian is also described as blue-eyed and ruddy (Sieglin 1935).