Bede in the eighth century described the Hartlepool headland as 'the place where deer come to drink.' The Angles named it Heruteu, Stag Island. Saint Aidan, an Irish priest, founded an abbey here in 640. Under Saint Hilda, abbess from 649 to 657, the monastery became one of the most important religious houses in Anglo-Saxon Northumbria. Hilda went on to found Whitby Abbey, where she presided over the Synod of 664. The Hartlepool monastery fell into decline in the early eighth century and was probably destroyed by Viking raiders in the ninth. The archaeological television programme Time Team located the foundations in March 2000, beneath St Hilda's Church on the headland. By 1153, Robert de Brus was Lord of Hartness, and the de Brus family held the lordship until 1306, when Robert the Bruce was crowned King of Scotland. Edward I promptly confiscated his English titles and began upgrading the town's military defences.

The town you see today is two towns welded together. Old Hartlepool stood on the headland, an ancient port that ran the County Palatine of Durham's official trade. The new town, West Hartlepool, was created in 1835 to handle coal from the South Durham coalfield, and grew explosively under the management of solicitor Ralph Ward Jackson from 1839 onward. The West Hartlepool Harbour and Dock opened on 1 June 1847, Jackson Dock followed in 1852 with a railway link to Leeds and Liverpool, and Swainson Dock followed in 1856, named after Jackson's father-in-law. By 1881, old Hartlepool had grown from 993 people to 12,361. West Hartlepool had 28,000. The William Gray shipyard in West Hartlepool claimed the world record for shipyard tonnage launched in 1878 and would do so again. Jackson, having built the town, was bankrupted by financial scandals and legal battles, and died near-poor in London. The two boroughs finally merged in 1967.

There is a legend, and the townspeople have decided to own it. During the Napoleonic Wars, the story goes, a French ship was wrecked off Hartlepool. Locals found a survivor on the beach: a monkey in a uniform, the ship's mascot dressed up by the crew for amusement. Never having seen either a Frenchman or a monkey, the locals decided this must be a French spy. They put it on trial. The monkey, unable to answer questions in any language they recognised, was found guilty. They hanged it. Whether any of this happened is uncertain. Folk songs, possibly originating in nearby Newcastle as a joke against Hartlepool, have spread the story for two centuries. Hartlepool United fans call themselves Monkey Hangers. The mascot of the town's football club is a monkey. In 2002, Stuart Drummond was elected Mayor of Hartlepool while running as the Hartlepool United mascot, H'Angus the Monkey, on a campaign promise of free bananas for schoolchildren. He served three terms. The story, true or not, is now an inextricable part of who Hartlepool is.

HMS Trincomalee is a Leda-class frigate launched in Bombay in 1817, two years after the Battle of Waterloo. She is the oldest British warship still afloat and one of the oldest in the world. She has been preserved at Hartlepool's marina since the 1980s, the centrepiece of the National Museum of the Royal Navy at Hartlepool, formerly known as the Historic Quay. Around her, the marina includes a re-creation of an eighteenth-century seaport, a 500-berth pleasure-craft basin, and the supporting Museum of Hartlepool. The Heugh Battery on the headland, one of the three batteries that returned fire on the German cruisers in 1914, is now an artillery museum run by the Heugh Gun Battery Trust. Hartlepool also hosts the Tall Ships' Races, which have called here in 2010 and 2023. The port itself, owned by PD Ports, still handles commercial traffic. Hartlepool United plays at Victoria Park. The town's population is about 92,600. The story it tells about itself includes shelling, shipyards, a monkey, and Anglo-Saxon saints. It is unusually complete.