Chen Chien-jen[3] OS KSG KHS (Chinese: 陳建仁; Wade–Giles: Chen2 Chien4-jen2, born 6 June 1951) is a Taiwanese epidemiologist and politician who served as vice president of the Republic of China from 2016 to 2020 and premier of the Republic of China (Taiwan) from 2023 to 2024 under President Tsai Ing-wen.

Later that year, Chen joined Tsai Ing-wen on the Democratic Progressive Party presidential ticket and served as Vice President of Taiwan from 2016 to 2020.

[8][9] He began his medical career by researching hepatitis B, and helped raise awareness about vaccination for the disease in Taiwan.

[19] On 16 November 2015, Chen was confirmed as the running mate for Tsai Ing-wen in the 2016 Taiwanese presidential election[20] after media speculation earlier in the month.

[27] Chen received international attention for his role in leading Taiwan's response to the COVID-19 pandemic due to his unique position as both vice president and his epidemiologist background.

[28][29] Days before he stepped down from the vice presidency, Chen stated that he would return to the Academia Sinica as a research fellow and thus forgo the pension connected to his political office.

[30] On May 17, 2019, the Legislative Yuan approved the same-sex marriage bill, Chen supported it by writing "The Executive Yuan has courageously assumed its responsibility, exercised its utmost wisdom and patience, and continuously communicated and coordinated with the pro and con sides in an effort to reduce social disagreements, proposing a bill that is consistent with the conclusion of the Justice's interpretation of the Constitution and responsive to the majority opinion of the referendum.

Chen and his wife were invited to visit the Vatican several times by Popes John Paul II, Benedict XVI, and Francis.