The interaction of robotics with biological, behavioural and brain sciences has always been tight. As often described in the literature, the living has often inspired the construction of robots. In this article, we focus on the reverse phenomenon: building robots can impact importantly the way we conceptualize behaviour and intelligence in animals and humans. After arguing that this two-way interaction has been present since the very first robots in the beginning of the 20th century, I analyze the spectrum of the various kinds of contributions that robotics has provided to behavioural and brain sciences. Based on a series of paradigmatic examples spanning from the modelling of insect navigation, the experimentation of the role of morphology to control walking, the self- organization of language in robot societies, and the use of robots as therapeutic tools for children with developmental disorders, I review the way robots can be used as operational models confronting specific theories to reality, or can be used as proof of concepts, or as conceptual exploration tools generating new hypotheses, or used as experimental set ups to uncover particular behavioural properties in animals or humans, or even used as therapeutic tools.