Zak (, also Romanized as Zāk) is a village in Darzab Rural District of the Central District of Mashhad County, Razavi Khorasan province, Iran.
At the 2006 National Census, its population was 1,095 in 276 households. The following census in 2011 counted 1,346 people in 386 households. The latest census in 2016 showed a population of 1,421 people in 406 households; it was the largest village in its rural district.
Zak is 6km north of Tus Iran. The distance of this village from Mashhad is about 36km. Most people are engaged in agriculture and animal husbandry, and most are engaged in wheat, barley and sugar beet.
The village has about 300 private villa gardens that are used for summer purposes.