Disambiguation: no secret identity; Vigilante's sidekick
First published in: 1942
Golden Age: Stuff, the Chinatown Kid first appeared as a sidekick to the Vigilante in Action Comics (DC, 1938 series) #45 (February 1942). Stuff was never given any other name, however both his grandfathers were named: Lin Choo in issues #45 (February 1942) - #47 (April 1942), and Mi Tu Sing in issue #97 (June 1946).
Pre-Crisis Earth-One: First appearance and death in World's Finest Comics (DC, 1941 series) #246 (August-September 1977).
Pre-Crisis Earth-Two: First appearance in DC Comics Presents (DC, 1978 series) #38 (October 1981).
Post-Crisis New Earth: First appearance in Young All-Stars (DC, 1987 series) #27 (July 1989). It was later revealed that The Vigilante actually had two sidekicks named Stuff, the brothers Danny and Victor Leong. According to Vigilante: City Lights, Prairie Justice (DC, 1995 series) #1 (November 1995), Danny was murdered at age 17 by Bugsy Siegel in November 1944. According to Stars and S.T.R.I.P.E. (DC, 1999 series) #9 (April 2000), Danny was murdered by The Dummy sometime prior to October 1948. According to El Diablo (DC, 1989 series) #12 (August 1990), Victor survived to the present day and became Greg Sanders' business partner. Based on on-sale dates, and assuming the November 1944 date, Danny was retroactively killed and replaced by his brother Vitor around Action Comics (DC, 1938 series) #80 (January 1945).
Link: https://en.wikipedia.org/wiki/Stuff_the_Chinatown_Kid