The design of new protocols for the colloidal synthesis of complex nanocrystals (NCs) with advanced functionalities, comprising both hybrid and hollow structures, and the study of their fundamental properties is of paramount importance for the development of a new generation of nanostructured materials. The possibility of tailoring the dimensional regime of NCs, along with its composition and structure, represents a landmark achievement in the control of their unique physico-chemical properties. These properties, alongside with the ability to cheaply produce high quality NCs in fairly large amounts by wet-chemistry techniques, leads to their potential applicability from materials science to nanomedicine. Within this context, this review is focused on describing a successful framework for designing synthetic strategies for the production of advanced complex NCs, integrating the development of new synthetic methods with its structural characterization, monitoring of their properties, and study of its reactivity. As a result, it is expected to provide new routes to produce robust and easy-to-process NCs in a wide range of sizes, shapes and configurations that can be explored to achieve the combination of all degrees of control, aiming to produce a complete and diverse library of material combinations that will expand its applicability in a wide diversity of fields. ; We acknowledge financial support from the Generalitat de Catalunya (2014-SGR-612), Spanish MICINN (MAT2012-33330 and CONSOLIDER2010-CSD 2008-0023-FUNCOAT) and European Community (EU FP7) through the FutureNanoNeeds project. N. G. B. thanks the Spanish MICINN for the financial support through the Juan de la Cierva program and European Commission for the Career Integration Grant (CIG)-Marie Curie Action. ; Peer Reviewed