Create your own comics with Storyboard That. You don’t need to sign up to start creating, but you will need to register if you want to save your stories. Just click on “Create a storyboard” in the top right of the main page.
The site is easy to use, with a drag-and-drop interface and plenty of choices for backgrounds and characters.
With a free account, you can make two stories per week, with 3 or 6 cells (boxes) each. In this free mode, all your stories are viewable and copiable by anyone. You can export your comics to Powerpoint, but the slides will have a watermark.