Tongerlongeter (c. 1790 – 20 June 1837) was a leader of the Poredareme clan of Aboriginal Tasmanians and a commanding figure of the Aboriginal resistance to British invasion during the Black War in Tasmania.

Details of Tongerlongeter's early life are sparse. He was born around the year 1790 into the precolonial Aboriginal society of the Poredareme group of people who resided along the coast and inland from Great Oyster Bay in Eastern Tasmania. By the 1810s, when the British started to encroach on Poredareme country, Tongerlongeter had become a tall, powerful and intelligent man.

European Seal hunters and whalers began exploiting Poredareme country during the late 1810s and early 1820s. They exhibited extreme violence against the local Aboriginal population, raiding their encampments, killing the men and abducting the women and girls into sexual slavery and forced labour. Those killed and kidnapped would have been well known to Tongerlongeter causing him and his people great anger and distress.

By 1823 and 1824, the prominent colonist, George Meredith, had established a settlement at Swansea and financed a number of sealing and whaling stations around Great Oyster Bay. Approximately forty other British settlers also entered the region at the same time, taking land from the Poredareme. This had a calamitous effect on the everyday life of the Aboriginal clan, forcing them to find ways to survive and resist an invading people who were alien, numerous and hostile.

In December 1823, hutkeepers at a recently taken up property at Grindstone Bay just north of what is now Triabunna, shot dead a Poredareme woman after abducting and raping her. A group of Poredareme men led by Black Jack (who was reportedly Tongerlongeter's brother) and Musquito (who was an Aboriginal outlaw originally from Sydney), led a reprisal attack on the hutkeepers killing two of them. Tongerlongeter was probably involved in this attack.

Groups of armed British men scoured the region for months afterwards, killing a considerable number of Poredareme. Musquito and Black Jack were captured and executed in February 1825. Despite this, the Poredareme, continued to resist occupation, attacking and killing colonists as the opportunity arose.

In 1826, another of Tongerlongeter's brothers was captured and executed. By this stage, Tongerlongeter, along with another Poredareme man named Kikatapula, had become leaders of what was left of the clan. He had seen many of his relatives and friends killed or abducted, and access to his ancestral lands had been removed. Revenge, as well as survival, became a focus of his continuing resistance. By 1827, a British Army military outpost consisting of 27 soldiers was established on Poredareme territory. Kickertopoller was captured in the same year, leaving Tongerlongeter in command of the remnant Poredareme and other Oyster Bay clans.

In 1828, most of the best land in Tasmania had been forcibly acquired by British colonists. The remaining Aboriginal people in the central and eastern parts of Tasmania numbered only several dozen, reduced by colonial violence from a pre-colonisation population of up to 2,000 people. Under these pressures, the remaining eastern Tasmanian Aboriginal people under Tongerlongeter amalgamated with the so-called "Big River" people whose country was the central part of the island and whose leader was a man named Montpelliatta.