Marquis Ai of Cai (蔡哀侯) (died 675 BC), born Jī Xiànwǔ (姫獻舞), was the thirteenth ruler of the State of Cai from 695 BC to 675 BC. He was the only known son of Marquis Huan of Cai (蔡桓侯), his predecessor. His reign was a period of 20 years. In the autumn of 684 BC, King Wen of Chu conquered the State of Cai and took the reigning Marquis as a prisoner of war. But King Wen of Chu restored the state after Marquis Ai praised Madam Xī (息妫). He was succeeded by his son.

蔡哀侯（？ - 前675年），姬姓，名獻舞，又稱蔡季，為春秋諸侯國蔡國君主之一，他為蔡桓侯胞弟，承襲蔡桓侯擔任該國君主，在位期間為前694年—前675年，共20年。

前684年，蔡哀侯娶陳國的女人，息侯也娶陳國的女人息媯。息媯將要出嫁到息國時經過蔡國。蔡哀侯說：「這是我的小姨子。」蔡哀侯叫息媯的隊伍停下，看息媯的容貌，強佔息媯。息侯聽說之後，非常生氣，請求楚國假裝攻打息國，息國假意求救於蔡國。然後楚國攻打蔡國，抓走了蔡哀侯。

前680年，蔡哀侯因為痛恨息國，故意在楚王面前誇息媯美貌。楚王於是滅了息國，將息媯帶回。息媯生下堵敖和成王，卻終日鬱鬱寡歡，一言不發。楚王為了討好息媯，硬說是蔡國滅了息國，於是發兵討伐蔡國。

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