It’s true! The name that we all know and love is actually a nickname; his given name is Scoobert Scooby-Doo!
The titular character wasn’t originally the mystery-solving Great Dane that we have now. Initially, he was a sidekick, a bongo-playing sheepdog/Great Dane whom creators from Hanna-Barbera named “Too Much.”
Doo was re-named by Fred Silverman who worked for CBS. According to what I could find he came up with the name from the Frank Sinatra song “Strangers In the Night”. There is a section at the end of the song where Sinatra says “doo-be-doo-be-doo” repeatedly while the music fades.
Another interesting tidbit, the original show “Scooby-Doo, Where are You!” was originally titled “Mysteries Five”.