  We study fixed subgroups of automorphisms of any large-type Artin group
$A_{\Gamma}$. We define a natural subgroup $\mathrm{Aut}_\Gamma(A_\Gamma)$ of
$\mathrm{Aut}(A_{\Gamma})$, and for every $\gamma \in
\mathrm{Aut}_\Gamma(A_\Gamma)$ we find the isomorphism type of
$\mathrm{Fix}(\gamma)$ and a generating set for a finite index subgroup. We
show that $\mathrm{Fix}(\gamma)$ is a finitely generated Artin group, with a
uniform bound on the rank in terms of the number of vertices of $\Gamma$.
Finally, we provide a natural geometric characterisation of the subgroup
$\mathrm{Aut}_\Gamma(A_\Gamma)$, which informally is the maximal subgroup of
$\mathrm{Aut}(A_\Gamma)$ leaving the Deligne complex of $A_{\Gamma}$ invariant.
