Magnetic liquid based deformable mirrors for all seasons and reasons. Denis Brousseau (U. Laval) Deformable mirrors are generally used for Astronomy but, during the past decade, their range of uses has increased to include ophthalmological, medical imaging, metrological and industrial applications. These new applications have stimulated the exploration of new deformable mirror concepts. Back in 2004, we presented a promising technology to build a liquid deformable mirror that uses a magnetic liquid whose surface is actuated by arrays of small electromagnetic coils. Several improvements have been made since that first proposal. I will present a status report of our research on these new deformable mirrors and explore potential scientific applications.