沙伊(Shai)，也拼写为萨伊(Sai)，偶尔也拼为谢伊(Shay)，希腊文中是普赛斯(Psais)，是埃及神话中命运概念的神化。作为一个抽象的概念，并不特指某一性别。多数情况下沙伊被当作男性神，但有时也认为是一女性神，在此情况下沙伊又称为“Shait”（女性化的名字）。该名字反映了她的作用，即意指“注定”。

作为命运之神，据说他决定每个人生命的长短，并出现在对死者灵魂审判的地府-杜亚特(Duat)中。因此，他有时被认为是生育女神梅斯赫奈特(Mesenet)的丈夫。在随后的几年中，又变成了赋予灵魂之一-瑞恩(Ren)、受尊敬的命运女神列涅努忒(Renenutet)的丈夫。由于这一概念与权力紧密相联。阿肯那顿(Akhenaten)在引入一神论(Monotheism)时说，沙伊是阿顿(Aten)的一个属性，而拉美西斯二世(Ramses II)自称是沙伊的主人(即命运之主)。

For the 1990s R&B group, see Shai (band); for the forebear of Mossad see Shai (Haganah unit).

Shai (also spelt Sai, occasionally Shay, and in Greek, Psais) was the deification of the concept of fate in Egyptian mythology. As a concept, with no particular reason for associating one gender over another, Shai was sometimes considered female, rather than the more usual understanding of being male, in which circumstance Shai was referred to as Shait (simply the feminine form of the name). His name reflects his function, as it means (that which is) ordained.