The main types of fullerene dimers synthesized so far, including the early all-carbon fullerene dimers, other new carbon allotropes containing two fullerene units and the specially interesting fullerene dimers bridged through electroactive spacers, are reviewed. The different synthetic strategies employed have been divided into two main types, namely: (i) dimerization of C60 itself or some C60 derivatives and (ii) bifunctional cycloaddition reactions to C60. These new systems are of interest since they can find applications in areas such as artificial photosynthesis, novel molecular electronic devices and in supramolecular chemistry.