Dr. Leonid Pavel (played by Alon Aboutboul) was a minor character in The Dark Knight Rises. He was a nuclear physicist who was kidnapped by the terrorist Bane and taken to Gotham City in order to create a nuclear bomb for him.
When Bane took the board of Wayne Enterprises hostage, he had Pavel, along with Lucius Fox, Miranda Tate and Anthony Fredericks use their fingerprints to unlock the fusion reactor located beneath the city so that its core could be removed. Once removed, the core began to degrade and would detonate in five months time.
Bane later blew up the Gotham Stadium pitch and made an address to the city, revealing his bomb and Dr. Pavel, the only man who could shut it down. He then killed Pavel by breaking his neck, ensuring that the bomb couldn't be stopped.