Christian Spencer Jessen (born 4 March 1977) is a British celebrity doctor, television personality, and writer. He is best known for appearing in the Channel 4 programmes Embarrassing Bodies (2007–2015) and Supersize vs Superskinny (2008–2014).

Jessen was educated at Uppingham School, a co-educational independent school situated in the small market town of Uppingham in Rutland, followed by University College London and the London School of Hygiene & Tropical Medicine, both constituent colleges of the University of London in Central London, where he received his MBBS degrees in 2001.

Jessen studied medicine as an undergraduate at University College London, graduating in 2001. He holds a MSc degree in sexual health, and has a particular interest in HIV and malaria, which were the focus of his work in Kenya and Uganda. An advocate for HIV education and testing, in 2015, he was named National HIV Testing Week Ambassador.

From 2007 to 2015, Jessen co-presented Embarrassing Bodies alongside Pixie McKenna and Dawn Harper. The show has had a number of spin-off series including Embarrassing Teenage Bodies, Embarrassing Bodies: Kids and Embarrassing Fat Bodies.

Another spin off was set in Australia in 2013 called Embarrassing Bodies Down Under, which Jessen co-hosted with Brad McKay, Ginni Mansberg, and Sam Hay.

He presented Channel 4's Supersize vs Superskinny series from 2008 until 2014.

In 2012, Jessen appeared as the health and fitness expert in Hotel GB. He was the winner of popular culinary show Ready Steady Cook and has appeared as a celebrity contestant on The Weakest Link.^{[citation needed]} He was also the winner of the BBC show Antiques Master.^{[citation needed]}

He was Jack Osbourne's doctor during the filming of Finding God, and also featured in Harley Street, a documentary. Other television appearances include Sex in Court and The Wright Stuff.^{[citation needed]}