In this Chapter we presents the spectral analysis of bounded linear operators, and for this we have presented some preliminaries on the spectrum of a bounded linear operator, and the eigenvalues of an operator, we follow we give some definitions on Compact operator self-adjoint, and also compact and normal operators. and we end with some examples on Nuclear Operators in the follow the  Chapter tow presents the Spectral Analysis of unitary linear operators, and for this we have presented some preliminaries on Spectrum of a unitary operator,, and the partition of the unit, we follow we give some definitions on .the Spectral Decomposition of a unitary operator.And we end with some notions for the spectral decomposition of a self-adjoint operator