  A mutual interplay between the charge and spin degrees of freedom in
itinerant magnets leads to a plethora of topological spin textures, such as
magnetic skyrmion and vortex crystals, in both centrosymmetric and
noncentrosymmetric hosts. Meanwhile, their stabilization has been extensively
studied in the system including the classical localized spins. We here study a
realization of the skyrmion crystal in the centrosymmetric triangular-lattice
Hubbard model, where the itinerant nature of electrons plays a more significant
role. By performing the self-consistent mean-field calculations, we find that
two types of skyrmion crystals with spatially nonuniform charge modulations
appear in the ground state at a zero magnetic field. Moreover, we obtain
another noncoplanar vortex crystal phase without a net scalar chirality in the
vicinity of the skyrmion crystal phase. We show that the latter vortex crystal
exhibits the topological phase transition to a different skyrmion phase in an
applied magnetic field. Our results provide a possibility of the skyrmion and
vortex crystals in itinerant magnets without the localized moments.
