Teresa Hsu Chih (Chinese: 许哲; pinyin: Xǔ Zhe) was a Chinese-born Singaporean social worker. She was known affectionately as "Singapore's Mother Teresa" for her active lifelong devotion in helping the aged sick and destitutes in Singapore. She was the founder of the non-profit charities Heart to Heart Service and the Home for the Aged Sick, one of the first homes for the aged sick in Singapore. Before coming to Singapore, Teresa had been a social worker in China and Paraguay and a nurse in England. She led a simple and humble lifestyle, and spent almost all her savings on feeding and housing the poor and the elderly.
As a supercentenarian, Teresa was still actively involved in charity work, and she has the distinction of being one of the very few supercentenarians who were recognized for reasons other than their longevity. She was the oldest living person in Singapore at the time of her death.