The influenza A virus (IAV) envelope protein haemagglutinin binds α2,6- or α2,3-linked sialic acid as host cell receptor. Bat IAV subtypes H17N10 and H18N11 form an exception to this rule and do not bind sialic acid but enter cells via MHC class II complexes. Here, we review current knowledge on IAV receptors with a focus on sialoglycan variants, protein co-receptors and alternative receptors that impact IAV attachment and internalization beyond the well-described sialic acid binding.