Bei Dao (simplified Chinese: 北岛; traditional Chinese: 北島; pinyin: Běi Dǎo; lit. 'Northern Island', born August 2, 1949) is the pen name of the Chinese-American writer Zhao Zhenkai (simplified Chinese: 赵振开; traditional Chinese: 趙振開; pinyin: Zhào Zhènkāi). Among the most acclaimed Chinese-language poets of his generation, he is often regarded as a candidate for the Nobel Prize in Literature. In addition to poetry, he is the author of short fiction, essays, and a memoir. Known as a dissident, he is a prominent representative of a school of poetry known variously in the West as "Misty" or "Obscure" Poetry.

Born in Beijing before the establishment of the People's Republic of China, Bei Dao served as a member of the Red Guards in his youth. However, disillusioned by the Cultural Revolution, he participated in the 1976 Tiananmen Incident and co-founded an influential literary journal, called Jintian (Today), that came to be officially banned in China. After his poetry and activism were an inspiration to the 1989 Tiananmen Square protests, Bei Dao was banned from China and entered a period of exile in the West, living and teaching in numerous countries before settling in the United States. He has been allowed to return to mainland China since 2006, but has not done so except for brief visits. In 2007, he joined the faculty of the Chinese University of Hong Kong. In 2009, he became an American citizen.

Bei Dao has been described as having played a significant role in creating a new form of poetry in Chinese literature, one that is often viewed as a reaction to the artistic strictures of the Mao era. In particular, his poetry is known for linguistic experimentation and an embrace of complexity, even paradox, in its exploration of individuality.

Currently, Bei Dao resides in Hong Kong, where he is an Honorary Professor of Humanities at the Chinese University of Hong Kong.

Bei Dao was born in Beijing, China, on August 2, 1949. He is the eldest of three children of Zhao Jinian (d. 2003), an insurance executive, and Zhao Mei Li (née Sun), a medical doctor.

Bei Dao was born into a notable family. On his father's side, he traces his lineage to the reign of the Kangxi Emperor, when his ancestor, Zhao Bingyan, was the provincial governor of Hunan and deputy minister of justice. During the Taiping Rebellion, his great-great grandfather, Zhao Jingxian, gained fame for defending the city of Huzhou against a rebel siege for more than two years. When the Xianfeng Emperor was informed of his death, he issued an imperial decree of praise, ordered reparations paid to the family, established an ancestral hall for the family in Huzhou, and recorded Zhao Jingxian's life in the Official Archive of National History. Bei Dao's great-grandfather was director of the Guangdong Manufacturing Bureau and retired as director of the Shanghai Manufacturing Bureau. However, due to war and internal strife in China, the family's fortune declined, and his paternal grandfather earned a modest living selling paintings and scrolls before dying when Bei Dao's father was still a child.

While his father's side of the family had been defenders and beneficiaries of the Qing Dynasty, Bei Dao's maternal side of the family played a role in overthrowing the empire. His maternal grandfather, Sun Haixia, was a member of the Tongmenghui society founded by Sun Yat-sen, who eventually became provisional president of post-imperial China. During the Wuchang Uprising, Sun Haixia was hailed as a hero for seizing a key telegraph station. In addition to founding a secondary school in Hubei, he later served as director of the telecommunications bureau of Chengdu and then directed the telecommunications bureau of Shanghai. After the establishment of the People's Republic of China, one of Bei Dao's maternal aunts was personal nurse to Mao Zedong's wife, Jiang Qing. Among his uncles, one was a deputy mayor of Wuhan, and another was vice chairman of the China Zhi Gong Party, one of eight political parties officially permitted in the People's Republic of China.

Bei Dao's father was self-educated and passed a test to gain employment at a bank. He was later a co-founder of the People's Insurance Company of China and a deputy secretary for propaganda for the China Association for Promoting Democracy (CAPD), a political party. Bei Dao's parents married in Shanghai and settled in Beijing the year before the poet's birth. They lived in the city's Xicheng District, which borders the Forbidden City and has been known as a home to the middle and upper classes. Bei Dao grew up on Sanbulao ("Three Never Old") Hutong, a street named for its most famous resident, Admiral Zheng He.