The Heavy are Pure Evils who have the most influence over the plot of the story. These Pure Evils may be the big bad themselves (Femto, Dio Brando, Musan Kibutsuji, Randall Boggs), but in many cases they could be the enforcer or right hand to the big bad (Saruman, Mahito, Nui Harime) to keep the big bad more mysterious and scary, especially when the big bad is non-action. They often appear multiple times throughout the story and have plenty of screen time. Often times, they will be the ones most active in terms of backstory and relation to the protagonists. Without them, there would be no story to begin with.

Famous examples include:

• Saruman from the Middle-earth film series. While Sauron is the main threat the Fellowship need to defeat, Saruman is the one who sends his forces after the Fellowship and wages war against Rohan.
• Femto from Berserk. While God Hand as a whole serves as the main antagonists of the series, Femto is the one most directly involved in the plot and serves as the most personal foe of Guts.
• Randall Boggs from Monsters, Inc. While Waternoose is the mastermind behind all the events, it is his right-hand man Randall who carries out his plan and acts as the direct threat to the heroes.

They are the Pure Evil counterpart of the heroes.