electron

https://doi.org/10.1351/goldbook.E01975
Elementary particle not affected by the strong force having a spin quantum number 1/2, a negative elementary charge and a rest mass of 0.000548579903(13) u.
Source:
Green Book, 2nd ed., p. 93 (https://dev.goldbook.iupac.org/files/pdf/green_book_2ed.pdf)