Kuanyin in Chinese / Japanese...

觀音/観音 is the Buddhist deity known as the Goddess of Mercy or Bodhisattva of Compassion.

In Chinese, the proper name of this being is Guan Yin. There is some debate as to whether Guan Yin is female. The argument comes from some scripture that suggests Buddhist deities take on the male form. Others say that Guan Yin has no sex. And still, others are okay with the female representation of Guan Yin.

This bodhisattva is also known or Romanized in the following ways:
Mandarin Chinese: Guan Yin, Kuan Yin, Kwan Yin.
Japanese: Kannon, Kwannon.
Sanskrit: Bodhisattva Avalokitesvara.
Korean: Gwan-eum.
Vietnamese: Quan Âm.
Thai: Kuan Eim.
English: Bodhisattva of Mercy and Salvation, Goddess of Compassion, Buddha of Mercy, et al.

Note: The first character has a slight variation in Japanese. If your audience is specifically Japanese, you may want to select that version.

See Also:  Buddhism | Goddess | Namo Amitabha | Bodhisattva

観音 is the specifically Japanese version of Bodhisattva of Compassion or Guan Yin.

In Japanese, this is pronounced Kannon and occasionally spelled Kwannon. The Chinese version is a bit more commonly seen in Asia. However, in Japanese, there is a slight variation with the first character.

Some time ago, a camera company in Japan named their company after this Buddhist deity. That camera company is still known as Canon (they chose a “C” instead of a “K” when they Romanized this name).

観世音 is the more extended and more formal Japanese version of Bodhisattva of Compassion or Guan Yin.

In Japanese, this is pronounced Kanzeon. The Chinese version is a bit more common in Asia, but in Japanese, they use a slight variation of the first character. Choose this version only if your intended audience is specifically Japanese.