Derek Tsang Kwok-cheung (曾國祥; born 8 November 1979) is a Hong Kong film director and actor. The son of actor Eric Tsang, Chi-wai Tsang got his start in the Hong Kong film industry working for director Peter Chan Ho-sun after graduating from the University of Toronto Scarborough in 2001. He made his acting debut in Men Suddenly in Black (2003) and directorial debut with Lover's Discourse (2010), sharing the directing credit with Jimmy Wan Chi-Man. The duo was nominated for a Golden Horse Award for Best New Director in 2010.

His solo directorial debut Soul Mate (2016) was critically praised, receiving a Hong Kong Film Award for Best Film nomination at the 36th Hong Kong Film Awards. His next film Better Days (2019) was the Hong Kong submission for the Academy Awards and received a Best International Feature Film nomination, becoming the first Hong Kong submission directed by a Hong Kong native to do so.

After graduation, he moved back to Hong Kong, where his father arranged for him to work under director Peter Chan Ho-sun. There, he met producer Jojo Hui and director Jimmy Wan Chi-man, both of whom would go on to be Tsang's frequent collaborators.

Despite not pursuing an acting career, Tsang has had a variety of acting roles since the start of his career, which he attributed to other actors not wanting to be typecast into roles with unflattering characteristics. He made his screen debut in Men Suddenly in Black (2003), cameoing as the younger version of his father's character. There he met director Pang Ho-cheung, whom Tsang would later collaborate with on various projects.

Tsang made his solo directorial debut with Soul Mate (2016). He was subsequently nominated for Best Director awards at various film award ceremonies, including at the 36th Hong Kong Film Awards and the 53rd Golden Horse Awards.

His next film, Better Days (2019), won eight out of 12 categories at the 39th Hong Kong Film Awards, including Best Film and Best Director. The film was subsequently chosen as the official entry for Hong Kong for Best International Feature Film at the 93rd Academy Awards. It was shortlisted but lost to Denmark's Another Round. He was the first native Hong Kong director in the category.

Tsang said his influences are primarily derived from art-house cinema, with early influences from director Wong Kar-wai and the French New Wave, as opposed to his father's works, which consisted of mostly of mainstream comedies.

Tsang married actress Venus Wong Yik-Man in 2019. He has expressed a reluctance to cast Wong due to the negative perception of nepotism.