Abstract: 
The existence of NonFermi liquids which are not described by Landau's Fermi liquids is a fascinating puzzle in theoretical physics. In this talk, I will show universal field theories where we can go around the Landau's Fermiliquids and obtain NonFermiLiquid behavior. These field theories contain dynamical singlet fermions which couple through fermion bilinear terms to strongly coupled sectors which are characterized by its ``dynamical scaling''. Suppose these strongly coupled sectors have gravity dual (which is not necessarily antide Sitter space), then by using powerful gauge/gravity duality, I will argue how these dynamical scaling parameters determine the natures of the dynamical singlet fermions in a very universal way; These natures include the existence of Fermi/NonFermi liquids, sharp Fermisurface, the decay rates and breakdown of the quasiparticles description. I will end with discussion for generalization of our work to include the lattice effects and impurities for more interesting condensed matter system.
