Execute is an ability in the Warhammer 40,000: Space Marine single-player campaign. When enemies become stunned, they are marked with a glowing skull icon and Captain Titus can "Execute" them with a special slow-motion finishing move to regain health. The only other way to heal in the campaign is to use Fury Mode, making Execution an essential mechanic.
Captain Titus executes his opponents in short slow motion animations. Generally there are 1–2 unique Exection animations for each weapon–enemy pair (e.g., one for finishing a Slugga Boy with the Combat Knife, two for finishing a Slugga Boy with the Chainsword, etc.)