[b]MegaCorporations[/b]
MegaCorporations started to emerge in the later years of the 20th and early years of the 21st century. Corporate entities that had such a broad and diverse range of departments, sub-companies and divisions that were dedicated to such a broad range of concerns and activities that the company had no one specialty or role. This began with tech companies and research and development companies, but soon other corporations diverged from their original businesses into more and more diverse areas. 
These companies likewise started to amass economic resources and wealth equalling some nations, if collected as a single entity. This also gave them a similar level of influence, control and power. 

These corporations started to register their head offices in countries with particularly relaxed laws and/or regulations, that further allowed them to expand their influence and control. As these countries were mainly poorer and unstable nations, they bought their way into government policies and decision making, as well as exercising considerable control over their defence and armed forces.
In these territories, contracts with the Corporations with controlling interest and that employ the majority of citizens are akin to indentured servitude. Access to goods, services, utilities, medical care, and even travel and identity documents can be restricted by the company and tied to company performance.
 
The security forces for many of these MegaCorporations were well-equipped and highly-trained enough that they were equivalent to private armies. Many of them had defence manufacturing divisions and capabilities, and equipped their own security forces with suitable weapons, equipment and resources to defend their own interests, or to act as Private Military Contractors. Local police forces are effectively corporate police as well, and favour outcomes for the company rather than private citizens or other people.

As yet, none of these MegaCorporations have taken control of or bought out - outright - any developed nations' government, but they have significant controlling interests and influence in the NCAA and the CAA. They have likewise never been confirmed to possess any weapons of mass destruction, but have the resources and capability to manufacture them. 

[b]UMC - Universal Manufacturing Congolmerate[/b]
Originally a purely mechanical and electronics manufacturing company, they have expanded into a wide variety of other areas, including farming, food production, medicine, telecommunications, consumer products, civilian and military vehicles, consumer, industrial and military electronics and a handful of smaller concerns. UMC may not be as well known as some of the other MegaCorporations, but were the first to pioneer and implement the manufacturing and production techniques for 'mass manufacturing' and 'autofactories' that enabled the replication and mass production of formerly discontinued products. 

[b]Montrose Incorporated[/b]
Getting their beginning in communications technology just after the First World War, they expanded drastically over the rest of the 20th century. Their primary physical products are electronic devices, but also have a huge area of business devoted to services, such as finance, law, insurance and other 'non-physical' products and services. Montrose are the biggest banking and finance company in the world, as well as being known for international law. Some of this reputation is notorious, as Montrose-affiliate lawyers have represented some of the worst and most notorious criminals known to the world, and successfully managed to acquit them of charges.

[b]NeoDyne Technologies[/b]
A company that formed from the merging and acquisition of several companies, they began as an manufacturer of machine tools. Over the years, they moved into manufacturing industrial machinery, electrical equipment, and then communications and computer equipment. From there, they expanded into medical technology, weapon technology, aerospace, marine engineering, heavy industrial, and into a wide array of business sectors. NeoDyne is probably the largest of the MegaCorporations with the most installations and facilities worldwide, and the most well known, with the highest number of employees and largest security forces.

[b]Silverfox Heavy Industries[/b]
Notable and remarkable as being the only Megacorp to be based in the N/UN and to adhere to their laws and regulations, they are nonetheless a huge and profitable corporation. Dealing primarily with the production of aerospace technologies, they also produce medical technology, medicine, heavy equipment and machinery, industrial, scienfic and military electronics, weapons and armaments and communications equipment.

[b]Misriah Ironworks[/b]
Misriah Ironworks began as a modest-sized small-arms and ammunition manufacturer, licence-producing weapons from other manufacturers and adding incremental changes, improvements and tweaks to the designs. Their success lead to greater orders and demand for their products, and in turn this allowed to expansion into other areas. Tools followed weapons, and then vehicles and their components, and from there they quickly expanded into every aspect of manufacturing of arms and armour; everything from bayonets to battleships. Military computing, communications and associated systems followed, along with private space launch, private security contracting and other associated fields. 
Misriah is the second-largest private military force next to NeoDyne, though with much greater breadth and range of military equipment and systems, and of a greater complexity and reliability.  

[b]Hegalia Aerospace Corporation[/b]
Hegalia Aerospace started out as a company that reconditioned aircraft, and had a small side-business licence producing aviation components. This business expanded and grew, with Hegalia licence producing complete aircraft before too long, as well as avionics and weapon systems for military aircraft as well as civilian aircraft. They followed with ground equipment, service equipment and vehicles, construction, and air traffic control and other operations. Chartered travel, instruction, and all of the administration and organisation around aerospace then followed and from there they moved into manufacture and support for all manner of vehicles, systems, transportation and all of the legal and paperwork services that related to those. 
Transportation of all kinds followed, and HAC became the world leader in travel and transportation, both services and hardware, as well as fuel and alternative fuels and supply of parts, though not without its' share of controversies and incidents, especially related to safety records.