Kwak or KWAK may refer to:
- Kwak (surname), a Korean surname (郭, 霍)
- KWAK (AM), a radio station (1240 AM) licensed to Stuttgart, Arkansas, United States
- KWAK-FM, a radio station (105.5 FM), licensed to Stuttgart, Arkansas, United States
- Pauwel Kwak, a Belgian beer
- Alfred J. Kwak, a cartoon television series
- Pieter Bas Kwak, professional esports player of Counter-Strike series
Kwak ( or ), spelled 곽 in hangul is a surname in Korea. The name can be traced as early as the Kim Silla kingdom. Today an estimated 187,000 people in Korea carry the name. They use the same Chinese character as the Guo/Kuo/Kwok of China. There are different transliterations of the name, but in South Korea, the emerging new spelling is Kwark, presumably following the lead of Park. Kwak is often mispronounced as Quack. Other variations of Kwak spelled by Koreans include Kwalk, Gwak, Kwark Kwalk, and Koak.
The Vietnamese use Quach. The Japanese use Kaku. The Chinese Indonesians use Kwik.