What is regarded as universal particle? Proton or Electron?

Proton:

A positively charged particle present in the nucleus of an atom is known as proton.

Electron:

A negatively charged particle which revolves in the circular orbits of an atom is known as electron.

Universal particle:

1. An electron is called a universal particle.
2. This is because the value of charge i.e. $1.6\times {10}^{-19}\mathrm{C}$ and the mass of electron i.e. $9.1\times {10}^{-31}\mathrm{kg}$ remains constant irrespective of the material into consideration.