Harbin (; Manchu: ᡥᠠᡵᠪᡳᠨ, Möllendorff: Halbin; simplified Chinese: 哈尔滨; traditional Chinese: 哈爾濱; pinyin: Hā'ěrbīn) is a sub-provincial city and the provincial capital and the largest city of Heilongjiang province, People's Republic of China, as well as the second largest city by urban population after Shenyang and largest city by metropolitan population (urban and rural together) in Northeast China. Harbin has direct jurisdiction over nine metropolitan districts, two county-level cities and seven counties, and is the eighth most populous Chinese city according to the 2020 census. The built-up area of Harbin (which consists of all districts except Shuangcheng and Acheng) had 5,841,929 inhabitants, while the total metropolitan population was up to 10,009,854, making it one of the 50 largest urban areas in the world.

Harbin, whose name was originally a Manchu word meaning "a place for drying fishing nets", grew from a small rural settlement on the Songhua River to become one of the largest cities in Northeast China. Founded in 1898 with the coming of the Chinese Eastern Railway, the city first prospered as a region inhabited by an overwhelming majority of immigrants from the Russian Empire. In the 1920s, the city was considered China's fashion capital since new designs from Paris and Moscow reached here first before arriving in Shanghai. From 1932 until 1945, Harbin was the largest city in the Imperial Japanese puppet state of Manchukuo.

Known for its bitterly cold winters, Harbin is heralded as the Ice City (冰城) for its winter tourism and recreations. Harbin is notable for its ice sculpture festival in the winter. Being well known for its historical Russian legacy and architecture—the city is famed for its European influence, and serves as an important gateway in Sino-Russian trade today. Harbin serves as a key political, economic, scientific, cultural and communications hub in Northeast China, as well as an important industrial base of the nation. The city was voted "China Top Tourist City" by the China National Tourism Administration in 2004.

Harbin is one of the top 100 cities and metropolitan areas in the world by scientific research output as tracked by the Nature Index. The city hosts several major universities in Northeast China, including Harbin Engineering, Harbin Medical, Northeast Agricultural, Harbin University of Science and Technology, Harbin Normal, Northeast Forestry, and Heilongjiang. Notably, Harbin Institute of Technology is consistently ranked as one of the best universities in the world for engineering.