  The production of electroweak bosons ($Z,\gamma$ and $W$) and charmonia is
sensitive to the initial-state geometry of heavy-ion collisions and to the
parton distribution function with its potential nuclear modification. Since
their leptonic decay products do not interact strongly, their kinematics are
unmodified by the strongly interacting medium, which can be created in a
heavy-ion collision. We report on the latest results of the ATLAS Collaboration
on electroweak boson and charmonia production in $p$+Pb collisions at
$\sqrt{s_{\rm NN}} = 5.02$ TeV. Production yields of $Z$ and $W$ bosons are
presented as a function of (pseudo-)rapidity in different centrality bins. The
forward-backward ratio of J/$\psi$ is shown as a function of transverse
momentum and center-of-mass rapidity.
