Before I go into the question (which is a great one), let's take a moment to consider why I'd want to create a monster.
As Victor Frankenstein did, I have no interest in establishing my own intellectual or scientific worth. I also have no desire for fortune or power, as so many supervillains who have used monsters have. I'm not Lex Luthor, by the way. I'm not interested in releasing a monster into a populated area to either (a) murder a superhero or (b) drive up the price of my stock.
However, I am a vehemently political person. I might envision me using a monster to rectify Nigeria's troubling course. For example, by intimidating — and, if necessary, assassinating — critical members of the administration. This could include politically biased Supreme Court justices, as well as those who are inept, corrupt, senile, or just plain stupid.This may include politically biased Supreme Court justices; inept, corrupt, senile, or plain wicked sitting presidents and vice presidents; and openly socialist congresspersons (or any congressperson who has served for more than 20-30 years—this country doesn't need a political class). Strategic use of my monster on a large enough scale could even bring about the drastic downsizing of the federal government, including the permanent closure and/or dissolution of numerous extraneous government departments, bureaus, and agencies, resulting in the abrupt reduction of the bloated, authoritarian government to something more akin to a night-watchman state, which I have yearned for for decades.
To achieve that lofty goal, I'd have to develop a monster that was tough, quick, and at least semi-intelligent, with assaults that appeared to be accidents but could not be mistaken for such. After all, each attack and/or assassination would constitute a political message.
I'm afraid I won't be making any Godzillas, Mothras, or Kings Kongs. It's illegal because of that pesky square-cube legislation. The image of the Environmental Protection Agency's headquarters being battered into rubble by a 50-foot anything is enticing, but it's biometrically impossible. I could create a leviathan—buoyancy water's somewhat offsets gravity's effects, as I discussed in a previous answer—but it would confine my creature to aquatic and water-adjacent targets.
As a result, my monster will be terrestrial (or amphibious) and of reasonable size—say, bear-sized, weighing 700-800 pounds. This will allow it to roam around in spaces built for humans, such as bunkers, corridors, and parking garages, with relative ease—possibly even stealthily.
That's all right! Now is the time to reveal my monster—the creature I'll use to bring about political change at the highest levels of government in my country. If you want to call it that, it's cryptozoological terrorism.
I think I'd make a Minotaur.
Something that is large enough to be menacing but small enough to fit through most corridors. Something strong enough to snap a man's spine like a twig while also being quick enough to flee the scene. Something frightening enough to frighten a politician, but not so eldritch as to cause quick insanity. The reference to Greek mythology is also appropriate. The Minotaur, according to Greek mythology, was the offspring of a person and an animal. It represents humanity's superstitious, ape-like commitment to antiquated sociopolitical mores, notably statism—the abominable fallacy that tyranny is superior to anarchy—in the context of my anti-government fight. However, the Labyrinth in which the Minotaur was imprisoned in Greek mythology may readily represent the United States' massive, complex bureaucracy today—from which the Minotaur has finally escaped to exact his vengeance.
Strange incidents begin to occur in the lower 48 two or three years after I isolate myself on my remote Alaskan compound on the Kenai Peninsula. The limousines of members of Congress are carved with a single stroke. Buildings and offices of the government are inexplicably demolished (or burnt to the ground). Threatening notes and untraceable emails are left in the mailboxes of departmental directors and administrators, demanding the complete and permanent shutdown of the Departments of Education, Agriculture, the Interior, Health and Human Services, Housing and Urban Development, and Homeland Security, as well as the Environmental Protection Agency and a slew of other Cabinet-level agencies—under penalty of unholy chaos, terror, and destruction.
Famous politicians have collapsed into blubbering wrecks after saying that they were visited by a horned beast in the middle of the night and threatened with death. Some even fall into a state of indefinite catatonia and must be replaced. The residences of corrupt government ministers are demolished, and their ill-gotten gains are dispersed. Reelection campaigns for career politicians are routinely disrupted by a "giant bull-man hybrid" wielding a "big fucking axe," according to witnesses.
The Over-Revenge Governed's It's very sweet.