The results of a systematic literature review conducted for variability modelling in software component models are analysed and presented here. A well-planned protocol guided the screening of 3230 papers that resulted in the identification of 55 papers. Reviewing these papers, 23 of them were considered as primary studies related to our research questions. A comparison framework is introduced to further understand, assess, and compare those selected papers. Observations about the important aspects of component models that support the variability capability are summarised. Prominent trends and approaches are discussed along with a comparative analysis of the component models. Only a few component models were found to be explicitly accommodating variability concerns. The identified variability modelling problems require further research for attaining better reuse capabilities.