Guan Yin (also spelled Kwan Yin) is the Chinese name of Avalokiteshvara, the Bodhisattva and incarnation of compassion and mercy.
Her full name is Guanshiyin which means "Observing the sounds (or cries) of the world." She represents mercy and compassion and is popular in the East and the West.
She takes various forms all over the world, in different eras and various forms. She can appear in the world as either male or female.

The Threefold Lotus Sutra describes Guan Yin as a Bodhisattva who can take any form. She can transform into a male, female, adult, child, elder, human, or non-human, in order to teach the Dharma. The Threefold Lotus Sutra states that Guan Yin has 33 different manifestations. Seven of these are female.
Representations of Guan Yin in the Song Dynasty were masculine in appearance. Images and statues of Guan Yin during this time later became both genders because of the Lotus Sutra. Because Guan Yin is considered to be the personification of compassion and kindness, and a mother-goddess as well as a patroness of mothers and sailor, the representation of the Bodhisattva became mostly female around the 12th century. In the modern period, Guan Yin is often depicted as a beautiful, young white-robed woman, a depiction which derives from the earlier Pandaravasini form.
In China, she is often depicted as young and beautiful, wearing white robes and a necklace of Indian/Chinese royalty. In the left hand she holds a vase that contains the elixir of immortality and in the right hand, she holds a willow branch. Guan Yin wears a crown with an image of Amitabha Buddha.
Guan Yin is a prominent figure in Journey to the West. One of the four classics of Chinese literature, it tells the tale of Tang Dynasty monk Chen Hui's epic pilgrimage with three other traveling companions. Guan Yin enlists Monkey King (Sun Wukong), previously imprisoned by the Buddha, to aid Chen Hui in his pilgrimage to India for Sutra and Reliquary. She later recruits Zhu Bajie (Pigsy) after his defeat at the staff of Monkey King, and Sha Wujing (Sandy) as a body guard for Chen Hui.
Guanyin has six parts representing her six qualities
This is the Japanese list
The Japanese Tendai school eventually adopted the new list, replacing Cundī with Amoghapasha (不空羂索觀音, Bùkōng Juànsuǒ Guānyīn; Jp. Fukū Kensaku / Kenjaku Kannon)