Captain-major is the English rendering of the Portuguese title Capitão-mor (sometimes Capitão Donatário) for colonial officers, put in charge of a capitania, Portuguesepossession (called captaincy, after his title) deemed not (yet) important enough to have its own colonial Governor.
This was notably the case in the following Portuguese colonies, but the list is probably incomplete:
Mazagan (El Jadida), since it became in 1506 a Portuguese possession, till 1608, afterwards it had its own Governors until on 11 March1769 it was incorporated into the sultanate of Morocco
Mombasa on the coast of later Kenya (since 1502 a sultanate, Mvita in Kiswahili or Manbasa in Arabic, independent from Kilwa Kisiwani) since its 1593 Portuguese occupation had captains-major (since 1638 as a Portuguese colony, subordinated to Goa in India), interrupted 12 December1698 by Omani sovereignty (under Governors styled Wali in Arabic, or Liwali in Kiswahili), then a last one as Portuguese rule resumed (12 March1728 - 21 September1729 Álvaro Caetano de Melo Castro, next it was lost for good - see also Colonial Heads of Mombasa
Mozambique, since 1 March1498 claimed for Portugal by Vasco da Gama, had captains-major since in 1501 Portuguese administration begins, as Captaincy of Sofala (subordinated to Goa, in India), till 1569, next Captains-general, since 1609 Governors, since march 1837 Governors-general - see also Colonial Heads of Mozambique
on São Tomé island, since it became a donataria in 1485, there were Captains-major till 1586, next Governors; 1753 it was united with Princepe island as (present state) São Tomé and Príncipe, again under Governors
South America
Brazilian provinces (some had Governors from the start):
Ceará, a captaincy since 1619 (1621-1656 subordinated to Maranhão), there were Captains-major 30 June1699- 17 January1799, then Ceará captaincy was split from Pernambuco (to which it had been subordinated since 1656) under its own Governor
Espríto Santo, which had been a donataria under its own Governors since 1535, had captains-major 1627-1675, then again two Governors Donatory, and more Captains-major 1682-1799 (though since 1718 it was a crown colony, subordinated to Bahia), afterwards again Governors
Grão-Pará had Captains-majors since in 1615 the Settlement begun as a part of Marahão (it was the residence of its Governors 1737-1755) - 1753, next Governors(-general)
Maranhão had Captains-major 1745 - 1775, next (as before since 9 January1616) Governors
since its creation in 1582 in the Captaincy of Paraíba, subordinated to Pernambuco, except the occuption (Dutch Directors 1635-1645) and the single 1645-1655 Junta (council), till 1797, next Governors; in 1799 a separate Captaincy of Paraíba do Norte was created
at least one Captain-Major is known of the Captaincy of Pernambuco (1535 founded as Donátaria of Nova Lusitania, renamed in 1575), Manuel de Mascarenhas Homem; no later then 1699 it got its own Governors, but nevertheless it became in 1716 a Crown colony, called captaincy of Pernambuco...
the 1597 founded Captaincy of Rio Grande had a single Captain-major 1697-1701, Bernardo Vieira de Mello, next Governors, subordinated to Pernambuco till 1808; since 1737 it got its modern name Rio Grande do Norte
at least since 1761 in the 1759 founded Captaincy of São José do Piauí, subordinated to Maranhão until 1811, from then with its own governors, since 28 February1821 renamed Province of Piauí
Sergipe d'el Rei had Captains-major since 1696 (also after the 1763 merger with Baía) till 20 February 1821, next it was a province under its own Governors
Asia
since 1518 (except in 1524 1551) a Portuguese Captain-major was appointed to Colombo, the capital of Kotte kingdom on Ceylon island (present Sri Lanka), until the last incumbent, Pedro Homem Pereira, was promoted to Governor in 1594; on 27 May1597, King Dharmapala of Kotte dies without heirs, and bequeaths his entire kingdom to the King of Portugal, making all Ceylon a Portuguese colony
since in 1557 the Portuguese established a trading post at Macau (subordinated to Goa in India), it had Captains-major till 1622, then Governors since 7 July1623 until 19 December1999 (finally returned to China)
East-Timor, a colony since 1642, had Captains at least since 1647, then Captains-major 1665-1702, next Governors
Ormus (present Hormuz, in Iran) had Captains-major both in September 1507 - January 1508 as the Portuguese first occupy it, again when since 1 April1515 Hormuz (Ormuz) Island became a Portuguese possession (subordinated to Goa in India), until its 3 May1622 incorporated into Persia
Malacca, since 24 August1511 a Portuguese colony on peninsular Malaysia, had Captains-major since 1512 (subordinated to Goa) till 14 January1641, next Captains-general, till is was list on 14 January1641 to the Dutch
Even smaller possessions could be under an officer simply styled Capitão (captain)
Such was the case in the following places:
(see also above for those who later got captains-majors):
Colonial captaincies in Africa
in Cape Verde the have been various captainships; only in 1587 the donatarias were united into colony under one Governor:
Aguz (Souira Guedima) during the entire 1506 - 1525 Portuguese rule there
Arzila (Asilah), since the 24 August1471 begin of Portuguese rule till 1545, afterwards it had its own governors (except August 1550 - 1577 temporarily restored to Morocco) until 1589 when it was for good restored to Morocco..