He better watch his back.

A Brit with a garish, Ben Affleck-like back tattoo has been added to Europe’s “most wanted” list, authorities said.

Shane O’Brien is wanted in connection to the death of 21-year-old Josh Hanson, killed with a stab in the neck at a bar in West London in 2015.

Europol released Europe’s most wanted list Friday and put out a $50,000 reward for information on O’Brien, 30 — who has drastically changed his look in recent years.

In a 2015 photo released by Scotland Yard, he was pictured with facial stubble, short hair and a “Shannon 15-04-06” back tattoo.

O’Brien was arrested in Prague in February 2017 on a criminal damage charge, but got out on bail because he used a fake identity.

By then, O’Brien gave himself a makeover, sporting a a full beard and shoulder-length hair.

He also had new ink — similar to Affleck’s famously tacky phoenix tattoo — of a huge owl with its wings spread carrying a skull, which covers up the “Shannon” tribute.

Affleck’s tattoo, which he once claimed was fake, depicts a phoenix rising from the ashes.