| Alex Tsai | |
| Honorific-Suffix: | MLY |
| Native Name: | 蔡正元 |
| Native Name Lang: | zh-tw |
| Office: | Member of the Legislative Yuan |
| Term Start: | 1 February 2008 |
| Term End: | 31 January 2016 |
| Constituency: | Taipei City Constituency 4 |
| Term Start1: | 1 February 2002 |
| Term End1: | 31 January 2008 |
| Constituency1: | Taipei City Constituency 1 |
| Office2: | Member of the National Assembly |
| Term Start2: | 20 May 1996 |
| Term End2: | 19 May 2000 |
| Birth Date: | 1953 12, df=yes |
| Birth Place: | Beigang, Yunlin, Taiwan |
| Nationality: | Republic of China |
| Party: | Kuomintang Congress Party Alliance (2018–2020) |
| Spouse: | |
| Successor: | Li Yanxiu |
Alex Tsai (; born 25 December 1953) is a Taiwanese politician and a member of the Kuomintang. He served as a legislator from 2008 to 2016.
Tsai graduated from the Taipei Municipal High School of Agriculture and Industry and the John F. Kennedy School of Government of Harvard University.[1] He was one of the 3rd members of the National Assembly.