James Mackenzie has become one of New Zealand's most enduring folk heroes. Few facts are known about his life or his brief public appearances, and doubt surrounds even his name: the correct spelling of Mackenzie is unclear and he is variously referred to as James, John or Jock. He may also have had at least one alias, John Douglass. Possibly born in Ross-shire, Scotland, in 1820, Mackenzie spoke Gaelic fluently but English only poorly, especially when under pressure. He claimed that his father had held a high position under the Crown and had died in Ceylon (Sri Lanka), leaving his family in needy circumstances. Mackenzie emigrated to Australia about 1849 and stated that, with the backing of an advance of £200 from his cousin Alister, or Alexander, McKenzie, high sheriff of Melbourne, he had purchased a team of bullocks and accumulated upwards of £1,000 by carrying goods to the gold-diggings. He then moved on to New Zealand. Disembarking at Nelson, Mackenzie worked his way through Canterbury to Otago, and claimed to have applied for a land licence in the Mataura district of Otago. He worked as a drover while waiting for the result of the land application.
In March 1855 Mackenzie was discovered with 1,000 sheep from Robert and George Rhodes's Levels station, north of Timaru. The station overseer, John Sidebottom, and two Maori shepherds had tracked the missing sheep to an inland pass in the basin of the upper Waitaki River, where they captured Mackenzie and found the tracks of several other men. Mackenzie denied the theft, claiming he had been hired by a John Mossman to drive the sheep to Otago. He then escaped and walked the 100 miles to Lyttelton, where, alerted by Sidebottom, Sergeant Edward Seager found and captured him.
After a preliminary hearing in March, Mackenzie was found guilty by a Lyttelton Supreme Court jury in April 1855, and sentenced to five years' hard labour on the roads. Unable to tolerate imprisonment, he escaped at least twice, in May and June 1855, neither escape lasting more than three days. After this he was placed in irons and carefully watched. In September 1855 Henry Tancred became resident magistrate at Christchurch. He investigated Mackenzie's case, found that the police inquiry and the trial had been seriously flawed, and with the support of Superintendent James FitzGerald, secured a free pardon for Mackenzie in January 1856. Mackenzie probably returned to Australia, but nothing certain is known of his later life. In the meantime the significance of the pass and of the pastoral country it led to were quickly appreciated, and Sidebottom himself was one of the first to take up a run in the Mackenzie Country, as it was subsequently named.
Mackenzie's exploits won him the admiration of those on the margins of society. Small would-be farmers wanting their own land or resenting the power of large wealthy landowners could identify with him, as could those who did not fit the mould of genteel Canterbury society. His rebelliousness and the triumph of his pardon won popular sympathy in a frontier society still engaged in establishing its social and political norms. The legends themselves reflect this. They emphasise his supposed superhuman strength, the feats of his fabulous dog, his extraordinary ability as a shepherd, drover and thief, and his rebellious spirit. In 1857 it was said that, after his escape from Sidebottom, Mackenzie stole a horse and galloped to Lyttelton, and the steady growth of the legend was recorded by Samuel Butler in A first year in Canterbury settlement (1863): '[Mackenzie's] boldness and skill won him sympathy and admiration.' The oral tradition has passed into more permanent media, ensuring that Mackenzie's exploits remain a potent myth.