A Military Brat is exactly what the name implies: someone who grew up with at least one parent in the military, sometimes both parents. Tends to crop up a lot in American series and works of fiction, particularly in times of Real Life conflicts when it can potentially make for a Reality Subtext, dealing with issues than many military brats might be experiencing in Real Life when their parents deploy.

In fiction, if a character has this as a backstory, you can expect at least one of the following to have affected him or her in some way:

• Having a very tough, conservative or strict upbringing;
• Frequent moves and parental absences;
• Sometimes a parent (often the father) will have died in some war.
• Lived on a base in a foreign country during their formative years, giving them an excuse for knowing an obscure foreign language or local custom. This might be West Germany, Japan, South Korea, etc.
• Or alternatively, having lived in a part of the U.S. where there is a lot of military infrastructure/installations - which almost invariably means the Deep South, Texas, or Washington, D.C., and never one of the other innumerable places in the US with large military installations (e.g. Fort Dix in New Jersey or, um, pretty much the entire city of San Diego, CA).

While there is definitely a Truth in Television aspect to this trope, it's important to note that:

• The US military contains several million people at any given time.
• Of the eight branches, seven have their own unique cultures. The Public Health Service Corps, commanded by the Surgeon General, and the NOAA Corps, who fly airplanes into hurricanes to measure wind-speed, temperature, and barometric pressure, aren't represented in the Pentagon and thus are often overlooked; the US Space Force is represented in The Pentagon, but didn't become a separate branch until 2019 and thus has yet to develop its own culture.
• Being the child of an officer is different from being the son/daughter of a non-com or an ordinary enlisted man or woman.
• Military culture changes over time. The US military today is not like it was during Vietnam, which was nothing like it was before World War II.^note Not least because the USA only had a skeleton-army up until 1940, with less than a hundred thousand troops available defend a country of 150 million. This would've been unimaginable for a country with enemies - 1913 Russia had maintained a standing army of a million, for instance. The tiny size and low mobility of the USA's army actually made Canada's defense plan in the event of a US invasion of Canada - a rapid motorised-cavalry offensive to take key transport hubs like Seattle, Chicago, New York, etc - workable.
• Despite the super-conformity image the military has, the people who serve in the military (and their families) still remain individuals with distinctive personalities.

Used often in war movies to explain why a character enlisted; the most common sub-explanation of this is that he wants to make his parent proud. A Military Brat may have a child who is, himself a Military Brat.

Despite the name, "brat" is mostly a neutral or even affectionate term, and characters with this background can be all over the place personality-wise. See also Circus Brat, which is sort of the opposite. Is never a Spoiled Brat, and usually dislikes parents who raise children such. Preacher's Kid often share features with this trope, as do missionary kids.

A related but markedly less badass version of this (which rarely appears in fiction) are the Foreign Service brats, whose childhoods were generally twisted by hopping around the world behind their parents. The same holds true for children of spies (said children, however, usually think that the parent is actually in the Foreign Service, some other government department, or occasionally some international corporation). The British word for this is diplobrat.

Military brats, foreign service brats, and missionary kids (though not preacher's kids) all fall within a larger category known as "third culture kids" (TCKs), usually defined as children who, for whatever reason, spend a significant part of their childhood outside their passport country.^note  Whether all military brats qualify as TCKs is a matter of dispute. Most "career military brats" in the US, defined as those who had a parent in the military from birth through high school graduation, do qualify by this definition, as most career military members spend at least one tour of duty overseas, and often more than one. However, a few career service members never go overseas, and many children are born to military parents who, for whatever reason, don't stay in the service until retirement. That said, military culture (whatever the country) is different enough from civilian culture that all but the most pedantic would extend TCK status to long-term military brats. TCKs can also include children of executives of international businesses or NGOs, as well as children of expatriate professional athletes. A notable example of the latter is Kobe Bryant, who spent a significant part of his childhood in Italy while his father was playing basketball in that country.

Naturally comes equipped with Dad the Veteran, even if it was Mom.

In many countries, this trope interleaves heavily with Blue Blood. Armed forces are the traditional career choice of aristocracy, and even today the children of old families of nobility are grossly over-represented in European and Asian forces.

This trope is also Older Than They Think. The Other Wiki calls American Military Brats a "200-year-old subculture". As mentioned, this changed throughout history, but most troops have historically had "Camp Followers" which were made up of the wives and children of the fighting forces, often serving in important behind-the-lines roles such as cooks, nurses, and errand runners. The most famous were probably those families that followed their husbands in Valley Forge, which would make Military Brats in the United States an older culture than the country proper.

Examples: