The stereotypical version of a boss is either somebody who resembles a drill sergeant, or some really condescending geek. While neither has been more than a stereotype, I can attest that there are people in leadership positions who can act like that sometimes. Some people do feel as if to be a good leader you have to stand your ground, and not allow for anyone else to question who is the boss. Other people really do feel as if the only way they can feel good about themselves is to show off their status, and how smart they are because of it.
In reality, a boss need not be either. A boss can show who is the leader without having to yell and scream, and he can be a leader without having to show off his smarts, or be condescending. In fact, a good boss really doesn't have to try to be anything, and can get the atttention of those around him just by his presence alone.
The best bosses that I have ever had are the ones who just know what they are doing. They realize that just like you, they have a job to do, and as long as it gets done the way it gets done isn't that important. They realize that people need to feel comfortable around you, and that being scary or intimidating isn't really a good way to boost morale.
Some people think that a boss has to be scary in order to get respect. A boos that needs to be scary in my mind is one who doesn't have respect, and has to rely on fear to scare people into working hard. A good boss should be able to relate to employees, and the use of a raised voice should be a last resort for a truly insubordinate employee, not a routine part of the verbal arsenal.
A boss should be open to advice, change, and sometimes criticism. It never hurts to have others be honest with you, and it allows you to grow and change as well. This is especially true if you are a younger boss, or have people working with you that have the experience that it takes to help you see things, and are able to help you mature into your role. We all need the help of our employees, and just because you are the boss doesn't mean you know everything.
A good boss will take the heat off of his employees, not apply more pressure. A good boss will take responsibility for the shortcomings of his employees, and not throw someone under the bus. There are times when an employee needs to be motivated, but to be constantly scared, or intimidated by your boss is not something I would want to go through.
Basically, a good boss is someone who is not intimidating. You need a true leader, and someone who can get the best out of his workers, and can accept input from them as well. Work is a two way street, and communication should be open on both ends, and this isn't accomplished by intimidation of employees. A good boss can work well with others, without having to scare them into working hard.