  Non-thermalized dark matter is a cosmologically valid alternative to the
paradigm of weakly interacting massive particles. For dark matter belonging to
a $Z_2$-odd sector that contains in addition a thermalized mediator particle,
dark matter production proceeds in general via both the freeze-in and superWIMP
mechanism. We highlight their interplay and emphasize the connection to
long-lived particles at colliders. For the explicit example of a colored
t-channel mediator model we map out the entire accessible parameter space,
cornered by bounds from the LHC, big bang nucleosynthesis and Lyman-alpha
forest observations, respectively. We discuss prospects for the HL- and HE-LHC.
