Sha Wu Jing - commonly referred to as "Sandy" in English - is a character from the Journey to the West (西游记 xī yóu jì) who was originally a God, but was cast out of Heaven for breaking a glass Zhan (盏 zhǎn)1 in a fit of rage.
1 A kind of small decorative cup, often floral in design.
Like Zhu Ba Jie (猪八戒 zhū bā jiè), Sha Wu Jing was originally a general in Heaven. He held a strange title, Juan Lian General (卷帘大将 juǎn lián dà jiàng) - where Juan Lian translates literally to "roll-up curtain"2 - and served under the Jade Emperor (玉帝 yù dì).
2 There is much debate over the meaning behind, and the rank of, the bizzare title "Roll-up Curtain General." Basically there are two schools of thought, the first being that this is a lowly title, held by a servant of the Jade Emperor who literally opens curtains, and other such fabrics/obstacles, as the Jade Emperor enters a room or wants to look out of a window, for example. The second is that this title belongs to a close and trusted advisor of the Jade Emperor, much like a secretary to the CEO, and is a noble title.
On a personal note, given that Sha Wu Jing was exiled to Earth for merely breaking a glass Zhan, I lean toward the former.
Before being exiled to Earth, the Jade Emperor had him struck 800 times with a rod and reincarnated him as a man-eating sand demon.