The above paintings are all covers from an RPG book series titled Fighting Fantasy which was published from 1982 through 95. It was designed for single players, similar to the Zork or Choose Your Own Adventure series. But unlike those series of books Fighting Fantasy used a dice system for combat and other situations. Read more about the book series here. The official website for Fighting Fantasy can be found here. This list shows all of the artists that contributed to the book series, the Ian Miller ones should be obvious.
Tomorrow I'll be posting more art associated with this series.