Internet of Things (IoT) is considered as the future of the Internet that connects billions of objects all together. Trusted communication between these objects is a crucial requirement for the wide deployment of IoT services. Consequently, effective authentication procedures should be applied between the communicating objects. This paper provides a comprehensive survey of object authentication in the IoT. The survey aims to direct future researchers in the field of IoT object authentication by delving into the details of authentication schemes and going through different comparisons. Comparisons are based on various criteria which include authentication process characteristics, the underlying architecture, key generation and distribution techniques, supporting IoT challenges, security analysis, and performance evaluation. Additionally, this survey highlights the main issues and challenges of IoT objects authentication and recommends future research directions.