Stevie Wonder began his career as Little Stevie Wonder, recording undistinguished albums of soul and big band covers under the creative control of Berry Gordy's Motown. At the age of 21 he threatened to quit the company unless he was allowed to do things his own way; Motown gave in, and Stevie Wonder went on to record a string of innovative albums that made him one of the key stars of the 1970s.
Henry Rollins was a scrawny bullied kid, until tenth grade, when he bought a weight set, hospitalized one of those bullies, and grew up to be a lot of things.
America took a level during World War II. Before the war, Denmark had a larger standing army than the USA. Then America split the atom, and from there, America became one of the two superpowers that would define the rest of the 20th century.
Technically America more harnessed the explosive power of splitting the atom, the first actually atom split was accomplished by a New-Zealand-born Brit, Ernest Rutherford.
Canada in World War I. Before entering, Canada was just some British colony overseas that no one really knew about. Afterwards, by the end of the war, German soldiers knew that if there were Canadian soldiers placed, they better prepare for an offensive attack.
During the war, the Germans referred to Canadian forces as Storm Troopers, the name used by Germany's own elite assault troops, responsible for pushing Western front back to the position attained in 1914.
xkcd took a level in badass IRL when Bill Amend drew a guest comic for it. A well known, high profile artist drawing for YOUR webcomic gives you prestige +9000.
Japan, 1850-2000: A fractious, feudal almost non-functional archipelago, on the verge of being colonised, pretty much modernised everything it can, and became a great power, being able to treat on equal terms with the likes of the United Kingdom, the German Empire, or the United States. She also leveraged its power into an empire of its own in the Pacific. Even after losing in WWII, Japan goes from an economy in shambles to an industrial and technological power-house that dominated the computer and car-manufacturing industry. Also, for a long time, it was the one of the very few, if not the only First World country, that wasn't predomiantly Caucasian. And as of 2014, it is still the third biggest economic superpower; a far cry from the backward, isolated, and unknown archipelago it was a mere 150 years ago.
Aron Ralston, upon whom 127 Hours is based. He spent three days with his arm trapped under a boulder, dying, then chopped his own arm off and legged it. He survived, obviously.
The Supreme Court took its level with Marbury v. Madison. It went from being the least powerful branch of the U.S. government to being able to nullify the actions of any of the other two (due to vagueness of the Constitution). Having a Chessmaster in John Marshall as a Chief Justice didn't hurt either.
Wild animals start out as tiny and very weak babies, only for them to grow up (if they survive long enough) and have things like venom, razor sharp claws and teeth, horns, antlers, tusks, fast speed, huge strength etc. You could say the same about humanity, for that matter.
The Kingdom of Prussia. What started out as merely one of the Electors of the Holy Roman Empire went and unified Germany by 1870.
Portugal was this, back during the Age of Discoveries. They basically had to go into this direction. In the North and East, there was Castille, waiting for a reason to invade. In the South, Portugal conquered Ceuta, just a little fort no one cared about. They did, however, discover a few little islands, and decided to explore more of the African coast. And the rest is history.
The British Army during The First World War. While its standing army was one of the most professional forces the isles have ever produced, it was miniscule. However, with a mass recruitment drive and a realisation that the Royal Navy could not end the war quickly, the Army turned from a highly-drilled minnow to a juggernaut to equal the French and German Armies - and, more than that, for all the talk of "lions led by donkeys", it was the British Army that most enthusiastically adopted the new technologies and concepts that WWI necessitated. By 1918, the tiny British Expeditionary Force had metastatized into the world's most mechanized army and the world's largest air force.
China. The country was arguably worse than Russia was through most of its existence. When Mao Tse-tung came along with his take on Communism in the late 40's, it only served to make things even worse. However, after the economic reforms by Mao's successor, in little over 60 years, it has become a global power that many believe even rivals the USA.
The Soviet Union in 1943. Before this time, it had a heavily outdated army devastated by internal strife, a populace that was uneducated and starving and a drought of scientific and technological progress. Hitler's armed forces almost destroyed the Soviet military, but after numerous counter-attacks (the most famous being Stalingrad) and a handy Russian Winter, the Soviets steam-rolled and conquered the Germans and invaded Japanese-held Manchuria. After that, they became a scientific, economic and military superpower, for a long time the only one capable of competing with the United States and the first nation to send a man into space.
Many of the most famous of war heroes come from rather humble beginnings. Simo Häyhä spent his life before the Winter War farming and hunting and started military service in a militia. Eddie Rickenbacker was the son of Swiss immigrants who was only educated until the age of 13 and nearly died in several varied accidents. Michael Wittmann was the son of a farmer and began his military service as a private.
Sharks. For a long time in their history, sharks were the butt monkeys for all manner of nastier sea-creatures. Sure, they were capable predators and numerous, but giant placoderms and mososaurs and bigger fish made life for them hell. That all changed after the KT Extinction Event. Sharks filled in the gaps left behind by the now-extinct aquatic predators and exploded into numerous variant species, living in every possible environment in the ocean, and becoming its top predators in many of those environments. It was only after the evolution of large toothed whales and dolphins like the sperm whale and orca that sharks had real competitors.
Speaking of evolution, everyone knows how Bad AssTyrannosaurus rex is, but not many people know that tyrannosaurs are coelurosaurs, NOT carnosaurs. In the Jurassic period, coelurosaurs were small, fluffy, and must have actually looked quite cute (Sinosauropteryx, the first known coelurosaur found with protofeathers, would be a good example.), but were Overshadowed by Awesome in the form of carnosaurs, spinosaurs, etc. However, come the Cretaceous period, the large meat-eaters of the Jurassic became old hat, and as they went into a decline, this left coelurosaurs with less competition. As you can imagine, SOMEONE *coughDilongcough* eventually thought it would be a good idea to crank the more advanced qualities of coelurosaurs Up to Eleven and take over the unoccupied apex predator spot that the carnosaurs had left behind, and history was made.
And speaking of dinosaurs, the T-Rex's bitter rival (at least on-screen) Triceratops was the end product of a long line of ceratopsian evolution that had rather humble origins. The very first ceratopsians were quite small, mostly ranging from dog to pig-sized. Some of them were truly strange, such as the bipedal Yinlong and the possibly amphibious Koreaceratops (This is a relatively recent discovery, so this may subject to change). However, towards the end of the Cretaceous period, the more recognizable four-legged, multiple large horned dinosaurs such as Triceratops, Torosaurus and Styracosaurus began to appear (though the bipedal line was still running around around the same time as their bigger, four-legged cousins). They and hadrosaurs had largely replaced the North American and Asian sauropod dinosaurs, much as the carnosaurs had largely been replaced by tyrannosaurs and dromaeosaurs in the same areas.
Ghengis Khan and the Mongols. He started off his "career" as a vassal to one of his father's friends, the tribes largely fractured and nomadic. By the end of his life he was the leader of a mighty, united Mongol Empire, becoming the scourge of the known world. His hordes carved out conquests that stretched from Siberia to Italy.
This applies to mammals as well. In the Mesozoic Era, the best they could really do was prey on young dinosaurs and other reptiles, and most of them were tiny, harmless critters that adapted to being nocturnal because of the intense competition. Their ancestors, the Synapsids, were fairly successful during the Permian period, but after the massive extinction that happened at the end made them into what could be called "The Chew Toy" of the animal kingdom. But, when the non-avian dinosaurs and other prehistoric reptiles kicked the bucket and ushered in the Cenozoic era, the mammals outcompeted every other vertebrate and became the dominant clade in the entire freakin' world.
Military training is designed to help recruits Take a Level in Badass via Training from Hell.
Fred Ettish, a karate instructor, was totally and humiliatingly curb-stomped in 1994 in UFC 2. He returns to CFX-Gladiator Evolution, 15 years later, then 53 years old, and proceed to demolish his opponent, who was almost 30 years younger than him. This naturally makes him a Badass Grandpa.
For diseases, the Shingles virus. Remember the Chicken Pox you had as a kid, the disease that probably didn't do anything besides make your skin splotchy and make you itch like an idiot for a few days? Well it remembers you, and as an adult, it can come back, donning a new name and the ability to effectively lights your skin on fire from the inside.
Audie Murphy, first when a German machine gun nest pretended to surrender then killed his friend. He killed them, captured the machine gun and several grenades and turned them on the Germans, destroying anything wearing the wrong uniform, then shut down completely. His biggest distinction was his Medal of Honour incident, where the tank destroyers supporting his company were almost completely wiped out, so when he ran out of ammunition in his M1 Carbine, he jumped on a burning tank destroyer and kept firing its turret mounted machine gun until it overheated and stopped working.
Two plants in the nightshade family got this after the Spanish explorations of the New World; the tomato and the potato. Both species of plant were relatively geographically isolated. The potato did not exist outside of what would be Peru and Bolivia, and the tomato was a part of the Aztec diet in Mexico. When the Conquistadores found them, they brought them to Europe, where both plant's popularity exploded. Try to imagine a world without potato chips, french fries, tomato sauce, barbecue sauce, sundried tomatoes or potato cannons! The potato in particular was especially important to the industrializing Europe, as the crop's heartiness and relatively cheap price kept millions in Ireland from starving (and did starve millions when a fungus caused the Potato Famine), fed millions more throughout Europe and was among the first crops grown in Europe's African and American colonies. It grew so popular that the potato became a subject of intense admiration. Marie Antoinette even wore a headdress made of potato flowers in appreciation of spuds everywhere. When the poster lady for the Ermine Cape Effect wears your reproductive organs as a hat, you know you've made it.
South Korea, in its formation it was small weak nation that got stomped by its Northern brother, today its an economic powerhouse, with an advanced standing army that out classes the outdated and poorly equipped North Korean army.
The National Aeronautics and Space Administration, and America's space program overall. Constantly lagging behind the Soviets in launching the first satellite, first mammal, first man, and first woman in space; it got so desperate President Kennedy brashly declared the United States would put a man on the moon first. The first official mission in this brash project, the Apollo program, saw the deaths of three astronauts on the launchpad. From such an abysmal low point, America succeeded in launching the first humans to actually enter deep space, rather than high orbit (Apollo 8), the first docking and undocking of space craft in lunar orbit (Apollos 9 & 10) and the fulfilled President Kennedy's declaration of putting a man on another celestial body (Apollo 11). Such was the badass of America's program that they even pulled off the successful return of astronauts after an explosion in space (Apollo 13).
But that's not the true level up. Not satisfied with beating their Russian rivals to the Moon, America then designs the first true spaceship (as opposed to one-off craft), the space shuttle, and among other moments of awesome including the Viking programs and the Mars rover, launched the first man-made object to leave the solar system and enter interstellar space. Took a Level In Awesome, indeed.
The Continental Army at Valley Forge. Marching in from a nasty defeat at Brandywine which cost the fledgling United States its capital, they wintered at Valley Forge, one of the geographicly worst sites in the State of Pennsylvania to camp an army through the winter. There they trained under Von Steubin a Prussian veteran, who ensured that by spring they could face the British Redcoats on nearly equal terms.
Niki Lauda. Just being a driver in Formula One during the seventies required a fair amount of badassery given the dangers involved with the sport (an average of two drivers killed or badly wounded per season). Within the measures of the sport, however, he was less daring than most other drivers and relied heavily on preparation and optimizing his car to minimize the risks. In 1976 he crashed at the Nürburgring track (having previously tried to get the race cancelled because of the risks involved) and was caught in his burning car for over a minute, receiving severe burns and damages to his lungs due to inhaling toxic fumes. His injuries were so bad that his wife brought in a priest to administer Last Rights. Lauda was back on the tracks a mere six weeks after the crash, very nearly won the championship that year and went on to win the following year. The man is a living legend for a reason.