How to Create a Character Bible for a TV Show

Your first step in creating your Character Bible is, simply put, a list of characters. You really need to take this time to hash out who your main characters are. The names of all of your protagonists and antagonists, as well as some re-occurring characters. It certainly can't help to figure a few of them out now! Keep in mind that your character bible can be flexible, and details about your characters can be re-written as you go along, but also make sure that you finalize them before you start writing your pilot.
Once you have your list of characters, your work on your character bible can begin! You will want to start on your main character first, and then branch out into the supporting cast. Basically, work on them in order of importance. A simple rule of developing characters that I have learned over the years is to follow one simple guide.

Always ask AND answer all of these questions about each and every character you are writing:
Where did they come from?
What happened to their past/family?
Who are they currently?
What are they currently doing?
What is their current life situation?
What is their physical appearance?
What is their dress?
What is their belief system?
What kind of personality do they have?
What is their current psychological makeup?
How do they act in social situations?
What kind of attitude do they have?
Who are their current connections/friends?
What kind of changes will the character make?
What is this characters immediate story arc objective?

Once you have answered every single one of these questions, in as much detail as you feel necessary, you are absolutely ready to write your characters into any situation when it comes time to write out the scripts. You can always use your bible for reference if you forget any details, and it will really help to ensure that you avoid continuity errors in your characters back stories, demeanor, etc.

Now that all of your characters have been thoroughly explored and fleshed out, it's time to grab yourself an artist! It's always a great idea to add some sketches of your characters, both static and in action, for your Character Bible. Variety is good, as it helps to give readers an easier time to really envision your characters and the world they inhabit. I like to have at least two static profile drawings of each character in two different outfits, and at least two drawings of them in an action pose as well.

Now your Character Bible is virtually complete! Much of what you have written and drawn here can (and probably will) be used in your pitch packet as well. So, take your Bible and start writing! Figure out who your characters really are.