This is it. This is the role Marty Feldman was born to play. Traditionally, Igor is depicted as a subservient figure, a lumbering fool who really only exists to say, "Yes, Master," and do the manual labor necessary for the great Frankenstein to achieve his goals. But this Igor...well, he's a little bit sarky. Upon learning that the young descendant of Dr. Frankenstein prefers to pronounce his last name as "Fronk-en-steen", presumably to distance himself from the lunatic behavior of his ancestor, Igor doesn't miss a beat before waspishly informing him that his name is pronounced, "Eye-gor". He gets some of the best lines in the film, and is such a strange, absurd human (why does his hunchback switch sides, anyway?) but at the same time incredibly loyal to the young Frankenstein. The dynamic between "straight man who holds everything in until one day he explodes" Gene Wilder and Feldman is perfectly balanced, and a huge part of what makes this film so successful.