Jacob Cornelius was a character in Darth Paper Strikes Back: An Origami Yoda Book that signed the petition to keep Dwight Tharp out of CREF. In the fanon, he has a brother named Grant Cornelius. Tom said of the character: "Jacob Cornelius, the kid at McQuarrie nobody actually knows!"
It has been theorized that JC (Harvey's cousin) is acctually Jacob Cornelius. This lacks logic however because Tom said Jacob goes to MacQuarrie and JC goes to another school so this theory is illogical. There is also an appearance of someone who may possibly have been Jacob Cornelius in the final book, Emperor Pickletine Rides the Bus, In which someone named Jacob is shown sitting next to Lisa on the bus seating chart.