Watchdog is a British consumer investigative journalism programme that was broadcast on BBC One from 14 July 1985 to 17 October 2019. The programme focused on investigating complaints and concerns made by viewers and consumers over problematic experiences with traders, retailers and other companies around the UK, over customer services, products, security, and possible fraudulent/criminal behaviour. Since it first began, the programme had achieved great success in changing the awareness consumers have of their purchasing rights, as well as pushing forward for changes in company policies and consumer laws, and in some cases helping to close down businesses whose practices have left many people dissatisfied and out of pocket. The show's longstanding slogan was "the programme you cannot afford to miss".

In the course of its history, Watchdog would spawn a number of spin-off shows, and be presented by a variety of hosts. It started as a feature on Nationwide in 1980 before it became a standalone series in 1985. After 35 years, and with more than a thousand episodes aired, the BBC announced in February 2020 that Watchdog would be discontinued as a standalone series, becoming a segment on The One Show to be presented by Matt Allwright and Nikki Fox on Wednesdays at 19:00.