Cook was married three times. He was first married to Wendy Snowden, whom he met at university, in 1963; they had two daughters, Lucy and Daisy; they divorced in 1971. Cook then married his second wife, model and actress Judy Huxtable, in 1973, the marriage formally ending in 1989 after they had been separated for some years. He married his third and final wife, Chiew Lin Chong, in 1989, to whom he remained married until his death. Cook became stepfather to Chong's daughter, Nina. Chong died at the age of 71 in November 2016.