Rebecca Loos (born June 20, 1978 in Madrid, Spain) is a former personal assistant to David Beckham. In April 2004, it was alleged that she was having an adulterous relationship with him.

The daughter of a Dutch diplomat and an English mother, Loos claimed that she became an "alternative wife" to Beckham after his move to Real Madrid. As Victoria Beckham remained in England to further her music career, she claims that she stepped in to help run his life and that this led to the affair. The claim generated a huge amount of publicity in the tabloid press, launching Loos's career as an ephemeral celebrity.