I do not know many groups (as in group theory) of quantum gates. Aside from trivial ones, I know there is Pauli group and the Clifford group. Recently I discovered another interesting group generated by $\sqrt{X}$ and controlled-$\sqrt{X}$ (NCV library). There is also the NOT, CNOT, Toffoli (NCT library).
What examples of groups that are
- discrete,
- have two or more generators,
- are not the same as the groups listed above but with a different Pauli gate,
- have at least a non-Clifford gate, and
- are not considered a universal gate set (like $\{H,T,\mathrm{CNOT}\}$)
are there?