Gan Wee Teck (simplified Chinese: 颜维德; traditional Chinese: 顏維德; pinyin: Yán Wéi Dé; Jyutping: Ngaan4 Wai4 Dak1; Pe̍h-ōe-jī: Gân Ûi-tek; born 11 March 1972) is a Malaysian-born Singaporean mathematician.

He is a Distinguished Professor of Mathematics at the National University of Singapore (NUS).

He is known for his work on automorphic forms and representation theory in the context of the Langlands program, especially the theory of theta correspondence, the Gan–Gross–Prasad conjecture and the Langlands program for Brylinski–Deligne covering groups.

Though born in Malaysia, Gan grew up in Singapore and attended Pei Hwa Presbyterian Primary School, the Chinese High School, and Hwa Chong Junior College.

He has also made contributions to the Gross–Prasad conjecture, the local Langlands correspondence and the representation theory of metaplectic groups.