Inconsistently Heinous villains who have significant periods in their character history where they are not a major threat to the heroes.

Some cases includes:

1. The villain's superpower were stripped off which they're no longer a main threat permanently or only for certain amount of time (e.g. Cassandra and Chrollo Lucilfer).
2. The villain has become a subservient to another character or other forces for whatever reasons (e.g. lost their legal authority, were cursed, etc.) after their defeat (e.g. Hordak).
3. The villain temporarily allying with the heroes to fight against a bigger threat than them or assisting something important to them out of reluctant or pragmatic reasons (e.g. two versions of Megatron, Ash Graven, Preston Northwest, Idate, Count Dooku, General Hux, Amanda the Adventurer, Azula, and Isabela Keyes). They can also have helped public or neutral characters on something (e.g. rebuilding a town, helping community, etc.).
4. The villain spends significant amount of time being imprisoned or taken as hostage on-screen (e.g. Clyde Shelton, Joy from Outside In, The Collector, Varrick, Kuvira, King Andrias, Notsussybaka900, Sheryl Goodspeed, Ztar, Catra, and Mr. Krabs from Mr. Krabs' Unquenchable Blood Lust). In some cases, they trying to break free. (e.g. Calamity Ganon, Dark Star, Discord and Solaris).
5. The story moves onto other villains/arcs or takes a break from drama which they are no longer the main or immediate focus on the heroes (e.g. Professor Poopypants, Aiden, Jet, Sunset Shimmer, Light Hope, SMG3, Dr. Saira Bellum, The Announcer, Itachi Uchiha, Orochimaru, and Tomura Shigaraki).
6. The villain is left alive or active after suffering a major defeat that either left them in permanently different condition or handicap. The villain then works with another character (e.g. Darth Vader, Jack Frost, Andrew Detmer, Ricky Chapman, Emperor Zarkon, Scaramouche, Annie Leonhart and the original version of Jason Voorhees).
7. The villain is exposed to toxins that brought out lighter qualities or something even better for a short amount of time. The villains under these instances such as possession, purification or brainwashing from an external source.
8. The villain's true colors are exposed to the public, which they is no longer a threat anymore and is currently hiding or on the run (e.g. Henry J. Waternoose III).
9. The villain spends significant chuck of the story hiding from the heroes instead of going in action. (e.g. King K. Rool).
10. The villain, for whatever reason, can only attack or commit evil actions at certain times and spends the rest of the time doing nothing (e.g. the Core).

It serves as an evil opposite of Inconsistently Admirable with Heating-Up Periods and a darker counterpart of On & Off villains.

NOTE: This category is different from On & Off because they are switching sides or committing heroic deeds from time to time while Inconsistently Heinous with Cooling-Off Periods have significant amount of time where they never did anything wrong or doing nothing instead of facing the heroes.