Professor Fang Hsi-ying is a leading world authority on mental illness.
He was the discoverer of the antidote to the poison of Rajaijah Juice that caused insanity in many. He is assisted by a man servant by the name of Chen. Tintin set out to find Fang after Wang Chen-Yee's son Didi had been driven insane by the Rajaijah poison. While on this quest Tintin met Chang, who would later become Wang's adoptive son. Fang was kidnapped by Mitsuhirato and used this to lure Tintin into a trap, which he survived, and was later able to rescue Professor Fang. He then cured Didi from the poison.
His name in Chinese characters is 方世英. Modern Mandarin Pinyin spelling of his name is Fāng Shìyīng. In the books the middle character of his name is written as 卋, a now-obsolete form of 世.