Christoffer Rodolphe van Hoogenhouck-Tulleken  known as Dr. Chris, is a British physician, television presenter, and identical twin brother of Alexander "Xand" van Hoogenhouck-Tulleken. Van Tulleken became well known for his two-part television special for BBC One entitled The Doctor Who Gave Up Drugs (2018). He is the author of Ultra-Processed People (2023). The van Tulleken brothers have jointly presented several television programmes, including the children's series Operation Ouch! (2013).