John Rogan was born in Hendersonville, Tennessee. He was the son of the former slave William Rogan, as the fourth of twelve children. His rapid growth began at the age of 13, due to gigantism.^[2] This led to ankylosis^[3] (an abnormal rigidity of the skeletal joints). By 1882, he could not stand or walk.

Although unable to perform physical labor due to his condition, Rogan made a living by selling portraits and postcards at a train station. An 1897 article in the Kansas City Journal mentions that a number of his drawings were published. He declined all offers to join carnivals and sideshows.

In 1899, he was measured at 8 ft 6 in (2.59 m), then tied with Franz Winkelmeier as the tallest person ever at the time. He weighed between 175 pounds (79 kg)^[1] and 205 pounds (93 kg), often billed in newspapers as the "negro giant" and "living skeleton".^[4] He used a goat-pulled cart like a wheelchair and was always the center of attention, often noted for his deep voice and playful attitude.^{[citation needed]}

Rogan's hands measured 11 in (28 cm) in length and his feet measured 13 in (33 cm) in length.^[1] Around the time of his death he measured 8 ft 9 in (2.67m). He was the tallest person of African descent and the second tallest person on record. Robert Wadlow's height surpassed Rogan's in 1939. A newspaper article said his maternal grandfather was also a giant, requiring a larger saddle when he rode horses, hinting at a possible genetic inheritance.^[1]

Rogan died on September 11, 1905, due to complications related to his condition. Evidence points to his burial having been on old Rogan farmland.^[4]

• List of tallest people