Neptune is an excellent free WordPress gallery theme. It's ideal for photography websites, online galleries and portfolios. It makes it easy to showcase all of your work in all its glory. The theme is easily customizable so even beginners can use it to build an impressive portfolio.
The theme comes with portfolio custom post type and unlimited portfolio categories so you can easily add and organize your items. There's also a neat image slider and a quicksand filter homepage gallery. This is a full-width template and it also includes a blog section.