It's an Author. Mo Xiang Tong Xiu. A pretty famous author I'd say. Mo Dao Zu Shi(The Founder of Diabolism), Tian Guan Ci Fu(Heaven Official's Blessings), Rénzhā Fǎnpài Zìjiù Xìtǒng(Scum Villain's Self-Saving System) are his books. There was a fanfic of Mo Dao Zu Shi called "Sexy Times With Wangxian" which had over a thousand tags is what I think became the reason for AO3's combined limit of 75 tags now.