Discovery of Electrons
1856-1940 Joseph John Thomson [Wikipedia]
1870-1942 Jean Baptiste Perrin [Wikipedia]
1861-1928 Emil Johann Wiechert [Wikipedia]
1851-1901 George Francis FitzGerald [Wikipedia]
1895 Jean Baptiste Perrin confirmed that the cathode rays carry negative charges using electroscope while Hertz had proposed that the cathode rays were a kind of electromagnetic wave. Later, J. J. Thomson revisited this experiment with several revisions to confirm Thomson's idea.

Jean Perrin
Nouvelles propriétés des rayons cathodiques
Comptes Rendus, Volume 121, pp. 1130-1134 (1895).
[Acad. Sci. France]

[English translation]
Jean Perrin
New experiments on the kathode rays
Nature, Volume 53, pp. 298-299 (1896).
[DOI] [Nature-Free-Text]
1897 Emil Wiechert
Ueber das Wesen der Elektrizität
Schriften der Physikalisch-Ökonomischen, Gesellschaft zu Königsberg, Volume 38, pp. 3-12 (1897).

Emil Wiechert
Experimentelles über die Kathodenstrahlen
Schriften der Physikalisch-Ökonomischen Gesellschaft zu Königsberg, Volume 38, pp. 12-16 (1897).

Emil Wiechert measured the value of m/e.
Assuming that the charge to be one electron, he made a conclusion that the mass of the particles, which constitute the cathode rays, was less than 1/400 of the mass of the hydrogen atoms. He stated ‘This upper bound for [the mass] shows unambiguously that cathode rays cannot be the ordinary chemical atoms.’
1897 Josseph John Thomson and "corpuscles", masses smaller than atoms

What he did
(1) The cathode rays can be bent with electric field !!
J. J. Thomson revisited Hertz's experiment with higher vacuum condition to elliminate possible shielding effects by ionized gases around the cathode rays. It worked!

(2) m/e is less than 1/1000 of H+. (cf. Wiechert's m/e was 1/400 of H+.)
He measured m/e in the conditions with many kinds of electrode materials and gases, and revealed that m/e was the same value for any conditions, which suggested that the "something" with m/e=1/1000 of H+ is common and fundamental substance of materials. Experimental results of Hertz and Lenard suggested that the "something" is smaller than atoms. However, it was just a speculation because "e" was not measured.

(3) He called the small something "corpuscle".

Josseph John Thomson
On the cathode rays (Monday, February 8, 1897)
Proceedings of the Cambridge Philosophical Society. Volume IX. October28, 1895--May 16, 1898
(Cambridge University Press, Cambridge, UK, 1898) pp. 243-244.

Josseph John Thomson
Cathode rays
Weekly evening meeting, Friday, April 30, 1897
Notices of the Proceedings at the Meetings
of the Members of the Royal Institution of Great Britain Volume XV. 1896--1898
(William Clowes and Sons, London, UK, 1899) pp. 419-432.
[Archive] [Archive] [Archive]

After these presentation, the following paper has been published.

J. J. Thomson
Cathode rays
London, Edinburgh, and Dublin Philosophical Magazaine Journal of Science 5th Series, Volume 44, pp. 293-316 (1897).

J. J. Thomson proposed "the existence of masses smaller than atoms"

J J Thomson
Saturday, September 16, On the existence of masses smaller than atoms
Report of the Sixty-Ninth Meeting of the British Association for the Advancement of Science
held at Dover in September 1899 (John Murray, London, 1900) pp. 637-637.

J. J. Thomson
On the masses of the ions in gases at low pressures
London, Edinburgh, and Dublin Philosophical Magazine Journal of Science 5th Series, Volume 48, pp. 547-567 (1899).

J.-J. Thomson
Indications relatives à la constitution de la matiére fournies par les recherches récentes sur le passage de l'électricité à travers les gaz
Rapports Présentés au Congrès International de Physique réuni a Paris en 1900
Rassemblés et Publiés par Ch. -Éd. Guillaume et L. Poincaré
Tome III (Volume III in Four Volumes)
(Gauthier-Villars, Paris, 1900) pp. 138-151.

Josseph John Thomson
The existence of bodies smaller than atoms (Royal Institution Lecture on April 19, 1901)
Notices of the Proceedings of the Meeting of the Members of the Royal Institution of Great Britain Volume XVI 1899--1901
(William Clowes and Sons, London, 1902) pp. 574-586.
1897 George Francis FitzGerald

He recognized J. J. Thomson's "corpuscles" as Stoney's "electron".

"As regards the calculation of the ratio of the numerical measure of the mass of the corpuscule to the electric charge it carries, there are two suggestions that can be made in respect of it. The first is that we are dealing with free electrons in these cathode rays."

George Francis FitzGerald's parents were William FitzGerald and Anne Frances Stoney. FitzGerald was the nephew of George Johnstone Stoney.

George F FitzGerald
Dissociation of atoms
The Electrician A Weekley Illustrated Journal of Electrical Engineering, Industry and Science, Volume 39, pp. 103-109 (May 21, 1897).