| Changa-Changa | |
|---|---|
| Chief of the Mashukulumbwe | |
 Purported photo of John Harrison Clark in later life in Broken Hill, Northern Rhodesia | |
| King of the Senga | |
| Reign | 1890s - 1902 |
| Predecessor | Monarchy established |
| Successor | Monarchy abolished; (Annexed by British South Africa Company) |
| Born | John Harrison Clark 10 May 1867 Port Elizabeth, South Africa |
| Died | 9 December 1927 (aged 60) Broken Hill, Northern Rhodesia |
| Spouses | Agnes Helen Cox Juvi Mphuka |
| Issue | John Harrison Burchmore Clark IV Celine Geraldine Harrison Clark |
| Father | John Harrison Clark II |
| Mother | Elizabeth Challen Clark |
| Religion | |
| Military career | |
| Allegiance | Cape Colony |
| Service | |
| Years of service | 1880s |
John Harrison Clark III or Changa-Changa (10 May 1860 – 9 December 1927) was an Anglo-South African explorer and adventurer who effectively ruled much of what is today southern Zambia from the early 1890s to 1902. He arrived alone from South Africa in about 1887, reputedly as an outlaw, and assembled and trained a private army of Senga natives that he used to drive off various bands of slave-raiders. He took control of a swathe of territory on the north bank of the Zambezi river, became known as Chief "Changa-Changa" and, through a series of treaties with local chiefs, gained mineral and labour concessions covering much of the region.
Starting in 1897, Clark attempted to secure protection for his holdings from the British South Africa Company. The Company took little notice of him. A local chief, Chintanda, complained to the Company in 1899 that Clark had secured his concessions while passing himself off as a Company official and had been collecting hut tax for at least two years under this pretence. The Company resolved to remove him from power, and did so in 1902. Clark then farmed for about two decades, with some success, and moved in the late 1910s to Broken Hill. There he became a prominent local figure, and a partner in the first licensed brewery in Northern Rhodesia. Remaining in Broken Hill for the rest of his life, he died there in 1927.