Though I don't know of any names, I think Einstein's explanation of photo-electric effect is not completely out of this world or without precedents. Quantizatio

Though I don't know of any names, I think Einstein's explanation of photo-electric effect is not completely out of this world or without precedents. Quantization was known though it was not applied to light earlier; Light's particle nature was considered earlier, though the double slit experiment convinced everyone that it's a wave. If I remember correctly Newton was of the opinion that light is particle in nature. Though it might have been hard to make the jump, I would assume that some smart guy would have been able to put these together and explain photo-electric effect, if Einstein hadn't. In a sense this achievement is more or less on the expected lines of progress for science. However Relativity is a huge leap in my opinion.