Lon, Lonnie, Al, Lonzo, Zo.
Famous people named Alonzo:
Basketball players Alonzo Mourning and Alonzo Gee; U.S. Congressman Alonzo Folger; Olympic runner Alonzo Babers; rapper Alonzo Mathis (a.k.a. Gorilla Zoe).
Alonzo has been in the top 1000 on the "most popular names" list since 1880, barely missing the top 100 at one point.