What is "Packy"?

Packy is one of the diminutive forms of the name Patrick used in Ireland (it has been said that there are as many diminutives for Patrick in Ireland as there are counties).

Are there famous Packys?

Indeed there are. In the late 19th and early 20th centuries, there was a boxer named Packey McFarland. Also in the early 20th century, a young man named Leslie Townes Hope boxed briefly and unsuccessfully under the nom de guerre Packy East; he later found success in vaudeville and in 1929 changed his name to Bob Hope.