There wasn't much subtlety to be found in the acronym given to the deadly creation of the subversive group of diabolical scientists called Advanced Idea Mechanics (better known by its own acronym, A.I.M.)--the weapon of destruction named MODOK, initials which stook for Mental Organism Designed Only for Killing. One of artist Jack Kirby's early masterpieces, MODOK was introduced in a two-part 1967 story featured in Tales Of Suspense as a new weapon in AIM's arsenal who would target his victims with extreme prejudice; but his dual purpose was as a powerful brain/computer that would exclusively serve the organization, perhaps to design even more sophisticated and powerful weaponry than AIM's in-house scientists could devise.
Over the years, and with his many appearances throughout a number of Marvel titles, MODOK's goals have branched off many times from what they were, though it's possible to select a number of interesting points of reference for the character and present them here as snapshots of his existence.
In both versions of his origin, MODOK was the result of an experiment conducted on a "volunteer"--one of AIM's agents picked at random whom the organization had no scruples in using as a guinea pig for what was apparently an unperfected procedure. The experiment worked too well; AIM had succeeded in evolving their subject into the weapon-computer they desired, but they failed to include sufficient safeguards that would bind their new creation to their will. Almost embarrassingly quickly, MODOK took over AIM completely and forced its agents and scientists into doing his bidding.
Not long afterward, S.H.I.E.L.D. (yeesh, it's raining acronyms--but you haven't seen anything yet) got wind of MODOK and sent one of their agents, Sharon Carter, to infiltrate and investigate--but Carter's status as a SHIELD agent was discovered by AIM, and Captain America was sent in to rescue her. When Cap arrives and begins taking action, we can see signs of how AIM's personnel are frustrated by and fearful of their newest creation.
Obviously MODOK's hold on AIM is both terrifying and intolerable to its personnel. But they catch a break when Cap and Carter raise enough of a ruckus to warrant MODOK's direct intervention--and this ghastly creation is finally unveiled.
Cap and Carter fight an uphill battle against MODOK, whose abilities are indeed impressive. But the oppressed AIM agents finally get the opening they've been waiting for, and they summon the courage to seize the chance to put an end to their rebellious oppressor.
Knowing a good villain when he had one, Lee would later resurrect MODOK and re-establish him as AIM's master--and for a time, MODOK became obsessed with bringing the Cube back under AIM's control. It's during the time MODOK spends in the early issues of Cap's book that Lee takes the opportunity to expand upon his origin.
(MODOK isn't likely to get any arguments from anyone on that "nightmare form" of his, thanks to the number Kirby did on him.)
MODOK's origin would get a more contemporary update with a few more details (though Lee essentially gave us the gist of the way it went down):
During his time with AIM, and taking advantage of its wealth of scientific equipment and resources, MODOK crossed over into other titles to pursue a number of insane schemes, none of them bearing fruit. Yet AIM inevitably reaches the point where it revolts against MODOK--and as MODOK attempts to regain control, AIM proceeds with a project as equally ambitious and horrific as the creation of MODOK. A project which they named (I kid you not):
Ms. MODOK was the result of AIM's procedure on another unwilling guinea pig--SHIELD agent Katherine Waynesboro, who fell into their clutches after MODOK's fall from power. Only this time, AIM intends not to repeat its earlier mistake with MODOK, and makes sure that the creature that emerges at the end of their procedure is fully loyal and subservient to AIM.
Unfortunately, when MODOK arrives to reclaim his command, the two intellects are drawn to each other, and Ms. MODOK turns on AIM just as MODOK did, while also agreeing to become his mate. MODOK would seem to have performed the coup of all coups, virtually securing his grip on AIM with this development; but when MODOK mercilessly destroys the Abomination, Ms. MODOK* is appalled at MODOK's lack of remorse and attacks him. MODOK responds in kind, and eventually forces her back into the grid from which she was formed, reversing the process and returning Kate Waynesboro to her former state.
(*You can't imagine how silly it feels to repeatedly use "MODOK" and "Ms. MODOK" in the same sentence.)
MODOK suffers a second death when AIM sends an agent of the Serpent Society to assassinate him.
AIM would later create another MODOK--this time from a female operative, which it afterward christened SODAM (Specialized Organism Designed for Aggressive Maneuvers) and sent her against two of the Avengers. In time, AIM restructures itself to become less an independent entity and more of a contractor available for the right price (and, as they put it, "a slice of the world's power pie")--and a powerful part of their "sales presentation" is their new mobile operative, renamed MODAM (Mobile Organism Designed for Aggressive Maneuvers). MODAM isn't so much a mentally evolved living computer as she is a specially-outfitted super-agent with advanced computer functions and weaponry (though she would indeed wield mental powers, as well). And this time, AIM makes sure that it made no slip-ups as far as MODAM's loyalties.
At one point, MODAM came into conflict with Superia, who had put together a group of "Femizons" that consisted in part of former agents of the Serpent Society, the very organization that put an end to MODOK. Ironically, MODAM was able to experience a hostile takeover from the perspective that AIM itself must have had when MODOK took over--only this time, Superia was attempting to seize control of AIM to suit her own plans. Unfortunately, Superia found that AIM, like MODAM, was not to be underestimated.
MODOK eventually returned, so MODAM wasn't around forever--but she was part of an interesting story involving a misstep by Tony Stark's company in selling nuclear materials to AIM, with Stark forced to travel to AIM's base in Boca Caliente and convince their CEO, Brannex, to resell them back. Stark, at the time paralyzed and confined to a wheelchair, decides to send a life-like facsimile in his place--but MODAM gets to the bottom of the deception with impressive efficiency.
The facsimile Stark is eliminated accordingly, which prompts Stark to mentally have Iron Man enter the fray--and we get quite a demonstration of MODAM's capabilities as well as her ruthlessness.
The situation becomes complicated for MODAM, however, when Omega Red enters the picture, convinced that he knows her true identity--a woman who once betrayed him, and who must now suffer his vengeance.
Iron Man intervenes before Omega Red slices MODAM into toast and manages to defeat both of them.
In light of the circumstances of MODOK's creation, it's difficult to shed any tears for AIM for having to give up its own agenda in research and development in order to be forced to serve a monstrosity that was created to serve them. All too quickly, AIM had to pivot from working in labs behind the scenes while moving quietly toward seizing the reins of world domination, to becoming MODOK's private army and being deployed or sacrificed in whatever way he felt was necessary in order to see his plans fulfilled. MODOK indeed became "the brains of the operation," as it were--created by brains that should have known better.
Whatever his problems with AIM, MODOK can always depend on the loyalty of his fans!