The fibre bundles adjoint to generalized almost quaternionic structures are studied. The most important classes of generalized almost quaternionic manifolds are considered. nionic affine space. A great contribution to the study of πAQ-structures was made by M.Obata [10] who investigated the structure of affine connections preserving πAQ-structure in parallel translations, as well as properties of transformations preserving πAQ-structure and by S.Ishihara who studied special types of πAQ-manifolds transformations [11].Soon the reseachers realized that the class of πAQ-structures is too narrow for constructing a self-contained quaternionic geometry: even a quaternionic projective space HP n does not possess the structure of such type. So, there was proposed (and it is generally accepted at present) a broader understanding of almost quaternionic structure as a subbundle of tensor bundle of type (1,1) on manifold whose type fibre is a quaternion algebra (or, equivalently, as GL(n, H·Sp(1)-structures on manifold [12]). Some authors called the structures almost quaternionic [13]. But the study of such structures by traditional methods was difficult as the structures are not strictly and globally defined by a given system of tensor fields like, for example, Riemannian, or almost Hermitian, or almost contact structures. Thus, the question of integrability of almost quaternionic structures is not answered at present (unlike πAQ-structures). Moreover, it is not clear yet in what terminology the integrability criterion could be formulated. Nevertheless, several interesting results in this direction were received, for example, Kulkarni theorem asserting that a compact simply-connected integrable quaternionic manifold is isometric to the quaternionic projective space [14].The most important results in the theory of almost quaternionic manifolds were received for quaternionic, quaternionic-Hermitian, quaternionic-Kaehler and hyper-Kaehler manifolds. Quaternionic manifolds were first considered by S.Salamon [15]. They are quaternionic counterpart of complex manifolds. Nevertheless, their geometry differs considerably from complex geometry, i.e. unlike Kaehler structures, a quaternionic-Kaehler structure is not always integrable. The basic property of quaternionic manifolds is integrability of a canonical almost complex structure on the space of their twistor bundle for manifolds of dimension greater than 4 [7] (in case of 4-dimension its integrability is known to be equivalent to manifold self-duality [16]). M.Berger proved [17] that quaternionic-Kaehler manifold of dimension greater then 4 is an Einsteinian manifold. It is Ricci-flat if and only if it is locally hyper-Kaehler. Otherwise, it is not even locally reducible. The author also showed [18] that compact oriented quaternionic-Kaehler manifold with positive sectional curvature is isometric to the canonical quaternionic projective space. Hyper-Kaehler structures were thoroughly investigated by A.Beaquville [19] who stated their close connection with complexsymplectic stru...