  Heavy charged lepton productions via gluon fusion at the LHC are revisited.
Full loop calculations are adopted with an updated parton distribution function
and electroweak data. Including contribution from new generation quarks in the
loop, pair production of the sequential heavy lepton via gluon fusion at the
LHC dominates over that via the Drell-Yan mechanism in some heavy lepton mass
range. Exotic lepton single production of vector-like lepton extended models is
also calculated. In the later case, the gluon fusion mechanism via the Higgs
exchange is emphasized. Our numerical results for both pair and single
production of heavy leptons are smaller than previous studies especially for a
large heavy lepton mass as a result of full loop calculation and due to the
mixing angles.
