Qamishli (Kurdish: Qamişlo, Arabic: القامشلي, Syriac: ܩܡܫܠܝ) is a city in northeastern Syria on the Syria–Turkey border, adjoining the city of Nusaybin in Turkey. The Jaghjagh River flows through the city. With a 2004 census population of 184,231, it is the ninth most-populous city in Syria and the second-largest in Al-Hasakah Governorate after Al-Hasakah. Qamishli has traditionally been a Christian Assyrian majority city, but is now predominantly populated by Kurds with large numbers of Arabs and Assyrians and a smaller number of Armenians. It is 680 kilometres (420 mi) northeast of Damascus.

The city is the administrative capital of the Qamishli District in Al-Hasakah Governorate, and the administrative center of Qamishli Subdistrict, consisting of 92 localities with a combined population of 232,095 in 2004. Qamishli was the de facto capital of the DAANES, until it was moved to Ayn Issa.

The city was initially a small village inhabited by Assyrians called ܒܝܬ ܙܠܝ̈ܢ (Bēṯ Zālīn) meaning "House of Reeds". The modern name is the Turkish calque of this name. Kamış means "reed" and -lı suffix denotes "place with" in Turkish.

The city was established in the 1920s by Assyrians escaping the Assyrian genocide who fled from northwestern Iran and southern Turkey. They built a small town under the French Mandate which they initially called Bet-Zalin. In 1926, it was renamed Qamishli and served as a station on the Taurus railway. One of the funders of the early development of the city was Masoud Asfar, an Assyrian who survived the Massacres of Diyarbakır (1895) as a young child. Masoud, along with stepbrother, whose last name was Najjar, established the Asfar & Najjar Corporation, a company that produced wheat in Qamishli. Throughout the 1920s–1940s, the Asfar & Najjar Corporation funded hospitals, Assyrian schools, and churches throughout the city. At the same time, many Armenians and Assyrians, fleeing persecution in Iraq and Turkey, moved into the region. This was followed by the emigration of Kurds from Turkey, most of whom settled in the countryside and then began to move to the city. However, in the 1960s and until the late 1970s, when Assyrians still constituted two-thirds of the city's population, the government of the Arab Socialist Ba'ath Party – Syria Region actively confiscated Assyrian farms, lands, and areas, causing an Assyrian exodus.

Qamishli is considered a center for both the Kurdish and the Assyrian ethnic groups in Syria. It was heavily settled by refugees from the Assyrian genocide. Assyrians were the majority in the city until the 1970s, when Kurds from the surrounding countryside moved into the city in numbers. Qamishli is renowned for its large Christmas parade, and Newroz and Kha b-Nisan festivals.

In March 2004, during a chaotic soccer match, the Qamishli riots began when visiting Arab fans from Deir ez-Zor started praising Saddam Hussein to taunt the Kurdish home fans. The riot expanded out of the stadium and weapons were used against people of Kurdish background. In the aftermath, at least 30 Kurds were killed as the Syrian security services took over the city.

In June 2005, thousands of Kurds demonstrated in Qamishli to protest the assassination of Sheikh Khaznawi, a Kurdish cleric in Syria, resulting in the death of one policeman and injury to four Kurdish civilians.

In March 2008, according to Human Rights Watch, three more Kurds were killed when Syrian security forces opened fire on people celebrating the spring festival of Newroz.