Responsible AI has been widely considered as one of the greatest scientific challenges of our time and the key to increase the adoption of AI. A number of AI ethics principles frameworks have been published recently. However, without further best practice guidance, practitioners are left with nothing much beyond truisms. Also, significant efforts have been placed at algorithm-level rather than system-level, mainly focusing on a subset of mathematics-amenable ethical principles (such as fairness). Nevertheless, ethical issues can occur at any step of the development lifecycle crosscutting many AI and non-AI components of systems beyond AI algorithms and models. To operationalize responsible AI from a system perspective, in this paper, we present a Responsible AI Pattern Catalogue based on the results of a Multivocal Literature Review (MLR). Rather than staying at the principle or algorithm level, we focus on patterns that AI system stakeholders can undertake in practice to ensure that the developed AI systems are responsible throughout the entire governance and engineering lifecycle. The Responsible AI Pattern Catalogue classifies the patterns into three groups: multi-level governance patterns, trustworthy process patterns, and responsible-AI-by-design product patterns. These patterns provide a systematic and actionable guidance for stakeholders to implement responsible AI.