Depends on what you mean by "unify" If you just mean "describe", then it's simple. We have the Standard Model with it's exceedingly simple Lagrangian Density formed by adding Yang - Mills & Dirac fields to Klein - Gordon fields.

$${\mathcal L} = - {1 \over 4}{F^{\mu\nu }}{F_{\mu \nu }} + i\overline \psi \not\nabla \psi + \overline \psi \phi \psi + \mbox{h.c.} + {\left| {\nabla \phi } \right|^2} - V(\phi ) $$

Here, it is easy to identify the Yang Mills field for gluons et al, the Dirac Fields for the quwarks et al, the Klein - Gordon for the Higgs, a scalar field.

If you mean "unify" in the sense of grand unification and such, then it's a bit more complicated.

# Grand Unification

Refers to the unification (meaning: having a simple group as the gauge group, as opposed to the Standard Model whose gauge group is $SU(3)\times SU(2)\times U(1)$; yet describe the Standard Model, since it's experimentally verified to a pretty high degree).

Examples include

# Theories of Everything

Better than GUTs; unify (quantised) gravity too. Examples include string-theory.