Lei is the pinyin romanization of the Chinese surname 雷 (Léi).

The surname is also romanized as Lui or Looi in Hokkien and Teochew; Lui, Looi, or Loi in Cantonese; Louie or Louis in Taishanese; Lūi in Gan.

Sino-Xenic pronunciations include Lôi in Vietnamese; Roe (뢰) or Noe (뇌) in Korean; and Rai in Japanese.

[2] In order, "Roe", "Louis", "Noe", "Louie", and "Lui" were all more common than the pinyin name; Loi and Rai were quite uncommon; and Leoi was held by fewer than 100 US residents and left unlisted by the Census Bureau.

[2] In Canada, Lei and Lui were among the 200 most common peculiarly Chinese-Canadian surnames found in a 2010 study by Baiju Shah & al, which data-mined the Registered Persons Database of Canadian health card recipients in the province of Ontario.