In imperial China, the personal name of the ruler had to be avoided in writing. Words were changed instead. For Emperor Wen of Han, Liu Heng, Mount Heng was written Mount Chang, and the moon goddess Heng’e became Chang’e, the name she still has. For Emperor Jing, Liu Qi, the spring solar term Qizhe became Jingzhe, and Qifeng county became Kaifeng.
A popular story holds that Guanshiyin, the bodhisattva of mercy, became Guanyin to avoid the name of Tang Taizong, Li Shimin. Chinese Wikipedia rejects it. Taizong required the taboo only when the two characters of his name appeared together, and the short form Guanyin was in use before the Tang.