I guess before 3rd edition, the role wasn't tied to a specific class.
Especially spellcasters (with the right spells) and archers fit the role best - they could strike at specific targets, circumventing other targets. Alone, they can be overrun easily, but with a strong defensive line, they were effective.
In 3rd edition, Classes like the Rogue, Ranger, Monk and Warlock are pretty close to that role - able to dish out lots of damage to single targets, but requiring to stay on the move or have someone else diverting the attacks to them. (Due to the mobility of many of them, they don't need a "defensive line" in the traditional sense, since they are all over the battle field. But they need someone that avoids them getting hammered by Greatclub wielding Ogres or recieving full attacks by Dragons)
The Striker role always existed, but no class was specialised for that role (but some where quite able to perform the role).