泰斯 is a generic transliteration of names ending in '-ais' or '-ess' sounds - most famously the title character of Massenet's 1894 opera 《
泰斯》 (Thais), based on Anatole France's novel about a 4th-century Alexandrian courtesan. Also used for Hardy's heroine Tess (more commonly
苔丝). Choose based on context.