  We propose the minimal and renormalizable non-supersymmetric top SU(5) models
where the $SU(5)\times SU(3)'_C \times SU(2)'_L \times U(1)'_Y$ gauge symmetry
is broken down to the Standard Model (SM) gauge symmetry at the TeV scale. The
first two families of the SM fermions are charged under $SU(3)'_C \times
SU(2)'_L \times U(1)'_Y$ while the third family is charged under SU(5). In the
minimal top SU(5) model, we show that the quark CKM mixing matrix can be
generated via dimension-five operators, and the proton decay problem can be
solved by fine-tuning the coefficients of the higher dimensional operators at
the order of $10^{-4}$. In the renormalizable top SU(5) model, we can explain
the quark CKM mixing matrix by introducing vector-like particles, and we do not
have proton decay problem. The models give rise to leptoquark and diquark gauge
bosons which violate both lepton and baryon numbers involving the third family
quarks and leptons. The current experimental limits for these particles is well
below the TeV scale. We also discuss the productions and decays of these new
gauge bosons, and their ensuing signals, as well as their reach at the LHC.
