The penultimate generation is the generation of Travelers before Bobby's. Prior to The Soldiers of Halla, Travelers from this generation were presumed to have fought Saint Dane themselves. In The Soldiers of Halla, it is revealed that the penultimate generation are actually spirits of Solara that were sent to the territories to guide the final generation Travelers throughout their childhood.
On Second Earth, Alexander Naymeer was supposed to be the penultimate Traveler, but Saint Dane interfered before he could do his job. Press stepped in as Bobby's mentor.
The only territory where the penultimate Traveler is unknown is Quillan.