Tondo (Tagalog: [tunˈdo]; Baybayin: ᜆᜓᜇᜓ, Kapampangan: Balen ning Tundo), also popularly known referred to as the Kingdom of Tondo, was a Tagalog and Kapampangan settlement which served as a major trade hub located on the northern part of the Pasig River delta on Luzon Island. Together with Maynila, the polity (bayan) which was also situated on the southern part of the Pasig River delta, Tondo established a shared monopoly on the trade of Chinese goods throughout the rest of the Philippine archipelago, making it an established force in trade throughout Southeast Asia and East Asia.

Tondo is one of the oldest historically documented settlements in the Philippines. It was mentioned in the Lord Namvaran's acquittance in 900 AD, also called the Laguna Copperplate Inscription, the oldest extant written document in the Philippines.

Manila, Tondo, and other Luzonian towns around Manila Bay and Laguna de Bay saw an influx of travelling Spanish warriors under Spanish royal command starting from 1570.

The Spaniards conspired to conquer the towns of Luzon for the Spanish king starting from the Manila Bay area. The Luzonian towns by the Manila Bay only started to capitulate to Spanish rule in 1571, including the traditional city of Manila (now called Intramuros), which was the capital of Luzon, and the town of Tondo. Tondo was afterwards ruled by the Spaniards from Manila.

Tondo's absorption into the Kingdom of the Spains and the Indies effectively ended its status as an independent political entity. It only regained sovereignty in the Philippine revolution, and then succumbed again to foreign rule after the American invasion, and has always remained a separate town until 1911 when Tondo was designated as a district of the modern City of Manila.

Geographically, the settlement was completely surrounded by bodies of water: mainly the Pasig River to the south and the shore of Manila Bay to the west, but also by several of the delta's rivulets: the Canal de la Reina to the southeast, the Estero de Sunog Apog to the northeast, and the Estero de Vitas on its eastern and northernmost boundaries.

It is referred to in academic circles as the "Tondo polity" or "Tondo settlement", and the earliest Tagalog dictionaries categorized it as a "bayan and Balayan in Kapampangan" (a "city-state", "country" or "polity", lit. '"settlement"').

Early travellers from monarchical cultures who had contacts with Tondo (including the Chinese, Portuguese and the Spanish) often initially referred to it as the "Kingdom of Tondo". Early Augustinian chronicler Pedro de San Buenaventura explained this to be an error as early as 1613 in his Vocabulario de la lengua tagala, but historian Vicente L. Rafael notes that the label was nevertheless later adapted by the popular literature of the Spanish colonial era because Spanish language writers of the time did not have the appropriate words for describing the complex power relations on which Maritime Southeast Asian leadership structures were built. The earliest Spanish accounts referred to Tondo as a smaller settlement compared to the fortified polity of Maynila, a characterization that reflects Spanish perceptions rather than the settlement's actual complexity.