PORTFOLIO-an edited collection of artwork (photos) intended to showcase an artist's style or method of work. - Wikipedia
Your portfolio may be as diverse as you need it to be. I have included the earliest photo of a play I did in high school, first headshot (in high school) all the way to my last head shot in 2010; ending with a still of me and cast members on the set of "Chase". Be as creative as possible. But, make sure your work is authentic, professional and clear.
HEAD SHOT - a photographic technique where the focus of the photograph is a person's face. - Wikipedia
Your headshot should look like YOU! Find a photographer who understands lighting, contrast and has worked with agents. Listed below are links to photographers I've used and reprographic agencies I've gotten printed copies from.