Ndumbé Lobé Bell or King Bell (c. 1839 – December 1897) was a leader of the Duala people in what is now the southern part of Cameroon during the period when the Germans established their colony of Kamerun. He was an astute politician and a highly successful businessman.

The first European records of the people of the Douala region around the Wouri estuary noted that they were engaged in fishing and agriculture to some extent, but primarily were traders with the people of the interior via the Wouri River and its tributaries, and via the Dibamba, Kwa Kwa and Mungo rivers. The main Duala communities at the mouth of the Wouri River were Bell Town, with the subordinate Bonapriso to the south and Bonaberi in the opposite shore of the river, and Akwa Town with the subordinate Deido to the north.

Douala was a dependable if minor source of slaves for the Atlantic Slave Trade. The British became active in suppressing the trade in the 1820s. In November 1829 the British ship "Eden" seized the Brazilian slave trader "Ismenia" of Rio de Janeiro after it had given its trade goods to the then King Bell for the purpose of obtaining slaves. On 7 March 1841, King Bell's predecessor signed a formal treaty with William Simpson Blount, commanding the British ship Pluto, in which he agreed to suppress the sale or transport of slaves in his territory.

With the abolition of slavery, the Duala people expanded their barter trade in palm oil, palm kernels and ivory from the interior in exchange for European goods. The practice of domestic slavery continued long after abolition of the overseas slave trade. Slaves were not necessarily mistreated. For example, David Mandessi Bell was brought as a slave from the Grassfields region into King Bell's household in the 1870s and became a rich and powerful member of the Bells, although he was not eligible to become chief.

An 1880 guide said the towns of King Bell and King Aqua, "separated only by a little brook, are apparently of great extent and considerable population. The houses are neatly built of bamboo, in wide and regular streets, with numerous plantain and cocoa-nut trees, and even large fields of maize... A considerable trade has been carried on for many years with the natives, who from their activity in collecting palm oil, and their intercourse with Europeans, have become a large and important community, possessing a high degree of civilization".

The Duala leaders, whom the Europeans called "kings", came from the two lineages of Bell and Akwa. In practice, both Bell and Akwa suffered from internal divisions and did not have strong control over their subordinate communities, who rivalled them in trade and at times took independent action. King Ndumbé Lobé Bell succeeded his father Lobé Bebe Bell in 1858, when he was aged about twenty. He was to lead the Bell faction for almost forty years until his death in 1897.

Between 1872 and 1874 there was a conflict between the Akwa and Bell factions over an attempt by Bonapriso to secede to Akwa. King Bell was supported by Deido, which had become independent of Akwa, in this struggle. In the late 1870s, King Bell managed to exploit a quarrel between the Akwa faction and the Kwa Kwa River traders to begin trading on this river, which leads to the much larger Sanaga River. Between 1882 and 1883, just before the German annexation, a violent dispute broke out between King Bell and three of his brothers, supported by Akwa and Bonaberi. These struggles were all harmful to the Bell trade.

By the later part of the 19th century the British were active in the Wouri estuary both as traders and missionaries and outnumbered the Germans, but accepted that the region fell within the German sphere of colonial authority. King Bell sought European protection to support his authority, prevent further attempts to defect by segments of his people such as the Bonaberi, and stabilise trade.