Pei () is an East Asian surname originating in north China. In 2008, it was the 156th most common surname in mainland China, with at least 830,000 Chinese sharing this name.
There are also people with this surname based on the same Chinese letter in Vietnam (as Bùi), where it is in relative terms much more common (the 9th most common surname), and Korea (as Bae; 배).
The surname Lei () was accidentally created from Pei as a result of a transcription error.
By coincidence, "Pei" is also an Italian surname (of two syllables), whose meaning may derive from the pear or pear tree, or alternatively, represent an abbreviation of "Pietro" or "Pompeo."