“To Dance is Human” (Hanna, 1979) but dancers on stage may be cyborgs, robots, avatars, or holograms. The boundaries between these creatures and their creators are sometimes blurred (voluntarily or not). The phenomenon is not new, but advances in technology (Including AI, Deep fake) broadens their use, strengthens this confusion and deepens the “uncanny valley” (Mori, 1970). If (modern, post-modern and contemporary) dance is challenging traditional spectatorship schemes in performing arts (often based on finding narrative interpretations), these Unidentified Dancing Beings (UDB) emphasizes dance specificities, forcing the spectators to question their relationship with dancing movements and their authors. Is movement still expression if it is automatically replicated by a robot? Can mirror neurons (Rizzolatti & Sinigaglia, 2008) be activated if these UDB are not recognised as congeners? Are the movements interpreted by the audience as icon and/or index and/ symbols? Are these movements “natural” enough to convince or do they create a trouble, “Unheimliche” (Freud, 1919)? The communication will attempt to answer these questions through examples in dance performances analysed with different semiotic theories (Eco, Barthes, Helbo, De Marinis, Ubersfeld, Pavis, Peirce, etc.); and will underline how this shift is editing spectator’s routine when attending performing arts in general and dance in particular.