A glutamatergic neuron, with a soma found in the deeper portion of L5, that has long-range axonal projections including deep subcortical targets outside of the telencephalon and, in some cases, the spinal cord. While the L5 ET neuron projections are not limited to ET targets, they are clearly differentiated from the neuron subclasses whose projections are constrained to intratelencephalic (IT) targets. L5 ET neurons are generally the largest excitatory cortical neurons, typically having a thick apical dendrite with a prominent dendritic tuft in layer 1 and displaying burst-firing physiological characteristics. [ http://dx.doi.org/10.1101/2020.10.19.343129 ]