Final answer:
J. J. Thomson, an English physicist, discovered the electron in 1897 through his work with cathode rays, leading to significant advancements in our understanding of atomic structure.
Step-by-step explanation:
The scientist credited with the discovery of the negatively charged subatomic particles known as electrons was the English physicist J. J. Thomson. In 1897, through his experiments with cathode rays, he was able to deduce the charge-to-mass ratio of electrons, revealing that they are indeed much less massive than atoms. Thomson's discovery led to his proposal of the 'plum pudding' model of the atom, where electrons were thought to be embedded in a positively charged 'pudding.'