When I was first starting on with table top RPGs a friend of mine pointed out that in their purest forms magical, stealthy, and brutish characters all balance each other out like a game of rock paper scissors.
Now I know once you get into more complex character options like a wizard in plate mail or the fighter that can sling spells lines get crossed and things get muddled, but I've always felt this was one of those core ideas that helped form how I see most of gaming. Just lie rock paper scissors is actually a metaphor for might money and mind where each aspect might seem like the obvious victor to different people while being completely susceptible to another so to do these aspects make for mighty heroes, but not perfect ones.
The sword or might aspect of things is your stereotypical fighter with a heavy emphasis on physical prowess while pushing mental ability to the side. He has the ability to crush anyone in his way and similar to rock might seem like the obvious victor in many situations, however magic can take him down in a heart beat. All his strength and power means nothing if a wizard gets into his head and starts pulling strings.
Speaking of magic second is the sorcerer or stereotypical wizard is the physically weakest of the three, but usually the smartest. Just like the concept of paper or money being able to buy might (this is what paper covers rock actually symbolizes) so to can a wizard bend even the universe to his will. That is until a rogue pops out of hiding and strikes him dead in a second,
Finally we have shadow or the stereotypical rogue. His strength lies in being unnoticed and thus is the least likely to be the target of the wizard's manipulation. When they leap from their hiding p[lace they usually do so with deadly accuracy, however that big bruiting fighter from the beginning usually has enough defenses or pure physical prowess to survive that first strike and once that moment is gone the rogue is left exposed and vulnerable.
These aren't absolutes in many games anymore as systems have evolved, but the core concepts still hold that the stealthy character hits the hardest in a single burst, the magical character are usually the weakest against physical attacks, and the big heavy hitting fighter types are able to take a hit better than anyone. This applies to settings outside of fantasy as well with tech being a substitute for magic and the fighter at times getting guns stretching his power out to a range, but the core holds true.