Professor Lenx is a Boar and a former teacher of math at Shiz University, before being fired for being an Animal. He is a character exclusive to the novels.
In A Lion Among Men, a wheelchair-bound Lenx is living in Rush Margins on the outskirts of Munchkinland with Mister Mikko, who is an ancient Ape. They both having taken up residence in the old cottage of Frexspar and Melena Thropp. The two of them interact with Brrr, where they discuss current events and past events. They soon rile Brrr up to retrieve money from the banks of Oz for them. The Lion soon becomes a broker for Animals, retrieving their money that is held in the banks since before they were forced to leave Oz.
In Out of Oz, it is revealed that Lenx had died some years after the events of A Lion Among Men.