Is Guanyin (Kwan Yin) found in Tibetan Buddhism?

Is Guanyin (Kwan Yin) found in Tibetan Buddhism?

Under the name Guanyin, no. Jetsun Dolma (Tara in Sanskrit) is the Bodhisattva of compassion and action, as Guanyin is in China. They are not the exact same, but they are the closest in similarities.

Guanyin is more of a "Mother Mary" figure in Chinese Buddhismthen Jetsun Dolma is in Tibetan Buddhism.

Om Mani Peme Hung

No. If I am not mistaken Guanyin is the Chinese version of Tara, who in Tibetan is called Jetsun Dolma. I know Jetsun Dolma and Guanyin are very similar, though have a slight different story behind them.

Yes, Guanyin is the Chinese version (depicted as a female) of the Buddhist Bodhisattva known in Sanskrit as Avalokiteshvara (depicted as a male), which is called Chenrezig (also depicted as a male) in Tibet. S/he (Buddhas and Bodhisattva's actually don't have a gender) is the Bodhisattva of compassion, which means a personification of enlightened compassion.