The third disciple of the monk 唐僧 in 西游记: a heavenly general banished for breaking a crystal cup, who carries the luggage west. Jokes say his only line is 师父被妖怪抓走了.
His surname 沙 'sand' comes from his home, the 流沙河 'Flowing Sand River', and 悟净 means 'awakened to purity'. As a river monster he ate travellers and wore nine skulls on a string, which he later ties into a raft to ferry his master across.