Electronic Journal of Differential Equations, Vol. 2023 (2023), No. 78, pp. 1-12. Title: Solutions for the Navier-Stokes equations with critical and subcritical fractional dissipation in Lei-Lin and Lei-Lin-Gevrey spaces Authors: Wilberclay G. Melo (Univ. Federal de Sergipe, Sao Cristovao, SE, Brazil) Nata F. Rocha (Univ. Estadual do Piaui, Teresina, PI, Brazil) Natielle dos Santos Costa (Univ. Federal de Sergipe, Sao Cristovao, SE, Brazil) Abstract: In this article, we prove the existence of a unique global solution for the critical case of the generalized Navier-Stokes equations in Lei-Lin and Lei-Lin-Gevrey spaces, by assuming that the initial data is small enough. Moreover, we obtain a unique local solution for the subcritical case of this system, for any initial data, in these same spaces. It is important to point out that our main result is obtained by discussing some properties of the solutions for the heat equation with fractional dissipation. Submitted April 18, 2023. Published November 10, 2023. Math Subject Classifications: 35A01, 35Q35, 42B37. Key Words: Navier-Stokes equations; global and local solutions; Lei-Lin-Gevrey spaces.