Yes, most people know me as "P.J. Healy", even though I use my
full name ("Paul J. Healy") for publishing and other official business.

The J. stands for Jay.

Homer Simpson has the same middle name:
Homer's middle name, "Jay," is a tribute by Simpsons creator Matt Groening to the work of cartoon producer Jay Ward, creator of Bullwinkle J. Moose and Rocket J. Squirrel.