Stellar content of TNG-Cluster halos: stellar mass of the central galaxy i.e. BCG (left), and total stellar mass of the halo i.e., the central galaxy together with the extended ICL as well as satellites (right). For central galaxy stellar mass we sum stars within r < 30 pkpc, and compare to abundance matching results (Behroozi et al. 2013, 2019; Moster et al. 2013, 2020) and observational inferences using similar definitions (Kravtsov et al. 2018; DeMaio et al. 2020; Akino et al. 2022). For total halo stellar mass we sum stars within r < r_500c, and also compare to data using similar definitions (Leauthaud et al. 2012; Gonzalez et al. 2013; Kravtsov et al. 2018; Chiu et al. 2018; Akino et al. 2022) as well as the Hydrangea simulations (Bahé et al. 2017).