The aim of this paper is to identify common features in: the definition of cyber terrorism, cyber terrorism targets, cyber terrorism crimes and then develop effective mitigation strategies and countermeasures to tackle this phenomenon. Through rigorous analysis of literature covering academic articles and official reports, we develop cyber terrorism definition taxonomy which includes five elements: target, motive, means, effect and intention; cyber terrorism targets taxonomy identified from the following target areas: military forces, government cyber and physical infrastructures, critical national infrastructures, social and national identity, and private industry and entities. The cyber terrorism risk factors are classified into main five categories: national security, financial, social and cultural, operational disruption and physical destructions risks. The following identified patterns constituted the cyber terrorism targets taxonomy: incursion, destruction, service interruption, disinformation and web sites defacement. The authors categorized effective strategic approaches to tackle cyber terrorism as: administrative, technological, national and local alliances, international alliances, and education, training and psychological approach. They developed cyber terrorism taxonomies which represent a systematic organization and classification of knowledge that improves scientific awareness of cyber terrorism definition, boundaries, potential targets, crime patterns and effective mitigation strategies.