Villains are necessary in most types of fictional novels. Although there isn't always an active antagonist, having one if you're just starting out can make creating a story easier.
The reason villains are helpful, is because they help generate or inspire conflict. Think about it seriously. If someone is living their life without antagonism, where is the growth?
Where is the change?
NUMBER ONE - Self
When the protagonist is his/her own villain, more work has to be placed into the plot points to advance conflict. Having triggers that inspire conflict within the character is always a good idea. (i.e., alcohol, social situations, addictions).
At the end of the day the internal conflict must stop the character from reaching his/her goal. Using a rich backstory can show how the protagonist himself continues to be in his own way.
NUMBER TWO - Inanimate Sources
A villain or antagonist doesn’t have to be a person. You can have inanimate objects or sources like the weather, a house, over even a computer. The primary thing to remember is the source must, as we already mentioned, stop your protagonist from reaching the goal.
NUMBER THREE - A Not So Bad Guy
Sometimes the villain doesn’t mean any harm. It’s just that what the protagonist wants, conflicts directly with what they want which increases conflict.
Think of parents, friends or even animals.
NUMBER FOUR - Straight Up Bad Guy
This villain wants nothing more than to take out your protagonist in an effort to obtain their goal. In most cases, the villain wants a version of what the protagonist wants, which causes the conflict to heighten. For instance, the hero may want to save a city. While a villain may want to rule the same city for financial gain.
Think about the type of character you want to create before penning your outline.
It will save you time and energy.
Also remember to have fun!