Part I of this thesis lays the foundations of categorical Demazure operators following the work of Anthony Joseph. In Joseph's work, the Demazure character formula is given a categorification by idempotent functors that also satisfy the braid relations. This thesis defines 2-functors on a category of modules over a half 2-Lie algebra and shows that they indeed categorify Joseph's functors. These categorical Demazure operators are shown to also be idempotent and are conjectured to satisfy the braid relations as well as give a further categorification of the Demazure character formula.Part II of this thesis gives a presentation of localized affine and degenerate affine Hecke algebras of arbitrary type in terms of weights of the polynomial subalgebra and varied Demazure-BGG type operators. The definition of a graded algebra is given whose category of finite-dimensional ungraded nilpotent modules is equivalent to the category of finite-dimensional modules over an associated degenerate affine Hecke algebra. Moreover, unlike the traditional grading on degenerate affine Hecke algebras, this grading factors through central characters, and thus gives a grading to the irreducible representations of the associated degenerate affine Hecke algebra. This paper extends the results of Rouquier, Brundan and Kleschev on the affine and degenerate affine Hecke algebras for GLn which are shown to be related to quiver Hecke algebras in type A, and also secretly carry a grading
