Colorlib offers some of the best free WordPress themes, responsive and full of options, ranging from business themes to blogs and portfolios.
Share bootstrap offers great free themes and templates built with Bootstrap. It is an especially great resource for Dashboard templates and themes.
Bootstrap Made offers free Bootstrap templates. They specialize in creating elegant, clean and beautiful free website templates using the Bootstrap framework.
A collection of 80+ free one page website templates. These free templates are great to quickly test your ideas before committing to a big project development.