The latest results from the LHCb experiment in heavy-ion collisions are reported. A variety of different collision systems is covered: proton-lead ($p$-Pb) collisions at $\sqrt{s_{\mathrm{NN}}}=5.02,\,8\,\mathrm{TeV}$; lead-lead (Pb-Pb) collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\,\mathrm{TeV}$ and proton-gas collisions in fixed-target configuration. These measurements exploit the forward geometry of the detector (pseudo-rapidity between 2 and 5) and thus are highly complementary to other measurements at the LHC. The measurements in $p$-Pb include the study of different heavy-flavour states, notably $B$ hadrons, $\Upsilon(nS)$, $\Lambda^{+}_{c}$ and coherent $J/\psi$ production in ultra-peripheral Pb-Pb collisions. In fixed-target configuration, $\overline{p}$ production in $p$-He collisions and charm production in $p$-He and $p$-Ar are covered.