Whizbang Dustyboots
Gnometown Hero
I'm old enough that I think of the iconic characters from the back of 1E's Rogues Gallery, many of whom were also name-checked in the PHB or DMG, or in later products.
I also think that Meepo and Ashardalon from the 3E era are NPCs that have stood the test of time.
I also think that Meepo and Ashardalon from the 3E era are NPCs that have stood the test of time.