
Runes have been a source of inspiration in D&D, probably since the beginning. Nordic rune magic can be seen in the old spell lists, but the journey from a few spells to the recent runepriest class isn't strait forward.
I've been pretty critical of the runepriest class in the past. I just don't like how it was implemented. For example, why strength as the key ability score? Constitution, at least, would make some sense given the lore of sacrifice to gain the power of runes. Wisdom as well, since runes have a tradition of insight about them, rather than intellectual cunning per se. What is interesting is the choice to make rune magic a type of divine magic, and labeling its wielders priests. There is a precedent for this, however. I'm going to stick just to the D&D examples of runes here though, rather than going afield into other RPGs.
Basic D&D
The first systematic predecessor to the runepriest that I've found so far comes in 1988. The Northern Reaches (GAZ7) for the basic D&D system doesn't present a specific class of rune-users, but instead gives northern priests access to a system of rune magic. I actually think its quite ingenious for the time. Rather than introducing a new runecaster class (see below), clerics gain access to a small series of second- and third-level rune spells (2 interpret, 2 bless, 3 know, and 3 inscribe rune), which they uses to access a system of runes.