Late-Northern-Sòng statesman, zì Yuáncháng 元長, of Xiānyóu 仙遊 (Fújiàn). Elder brother of 蔡卞 Cài Biàn. Dominant chief councillor under Huīzōng (1102–1120, with intervals), architect of the post-Yuányòu reformist consolidation and of the “Yuányòu blacklist” (the proscription of Yuányòu-era officials including 蘇軾 Sū Shì, 程頤 Chéng Yí, and 司馬光 Sīmǎ Guāng). The principal target of 陳瓘 Chén Guàn’s life-long campaign of impeachment memorials; conventionally regarded by Sòng historiography as one of the jiānchén 奸臣 (“treacherous ministers”) who brought about the Jīngkāng catastrophe (1126–1127).