With the expected superior performance to the current generation of mobile networks, fifth generation (5G) systems are poised to support new and diverse usage scenarios and applications, thus enriching the lives of citizens and the productivity of industry and public sectors. The widely accepted scenarios for 5G include enhanced mobile broadband (eMBB), addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable low-latency communications (URLLC) with strict requirements, especially in terms of latency and reliability; and massive machine type communications (mMTC) for a very large number of connected devices typically transmitting a relatively low volume of non-delay-sensitive data. This Special Issue (SI) of IEEE Network aims at presenting the most relevant scenarios, prominent research outcomes, and state-of-the-art advances of 5G systems for URLLC achieving the Third Generation Partnership Project (3GPP) targets on latency and reliability requirements to successfully deliver delay-sensitive information. In 3GPP, the performance target for control plane latency is 10 ms, and for user plane latency it is 0.5 ms for downlink and uplink directions, separately.