Final Activity Report Summary - MSEPOA (Multi-wavelength searches of the elusive population of obscured AGN) The main objective of our project is the systematic study of the properties of Active Galactic Nuclei (AGN) and their environments, on the basis of multi-wavelength observations and in particular to isolate those AGN whose properties indicate that their central engine is heavily obscured by dust. Combining the expertise and unique datasets to which the involved scientists have access to, is one of the main assets of our research project.A comprehensive catalogue of all identified sources in the northern and southern fields of the GOODS survey (of which the fellow is member) was established (Vizier), while at the same time a catalogue of obscured AGN from the XMM survey (to which the host team has access) was established (http://aiantas.astro.noa.gr/~dathanas/sheep1cat.html). Both catalogues contain full multi-wavelength information for all sources. Constructing the full Spectral Energy Distributions (SEDs) we detected several obscured AGN that in the optical wavelengths remained heavily obscured by large amounts of dust, dominated mostly by star light. We examined the host structural properties and AGN environments, but did not find a strong correlation between galaxy merging and AGN activity, besides a trend with AGN luminosity.Another line of research concerned the study of a particular type of active galaxies, the BAL QSOs, which are quasars sustaining large scale outflows that obscure the quasar continuum and broad emission lines. We approached this topic from both the perspective of a spectroscopic survey of a statistically significant sample, as well as the detailed modeling of the spectra of selected objects. Our results indicative that radiatively accelerated winds is the most probable mechanism and allowed us to constrain the physical parameters (outflow velocities and geometries) within a range of possible best fit values.It is thus clear that the realisation of the project has helped to promote the professional reintegration of the fellow in her home country, as well as, has helped expanding her fields of expertise and research activities and those of the host group. Beyond her research activities, the fellow has also been very active in carrying out educational and dissemination activities targeting the general public, in order to demonstrate the impact of the research and science results for the society at large.