The stereotype of the Mafia or mysterious evil villain has been a popular theme in games, tv shows, and movies. And let's face it, who doesn't love a good mob movie? In this section I compare Giovanni to a few personalities that are similar.
Karen was so kind enough to bring Don Vito Corelone to my attention. Part of me was wondering how I could have possibly overlooked this character and his relation to Giovanni. Vito is the "the Boss" character in the 1972 film The Godfather. Vito could well have been another character that Giovanni was based on. He has the typical Italian mobster dress, the slick hair, and like Giovanni, also has a pet cat. Corelone is the head of many operations and also has political influence, much like Giovanni. He is, however, a much more ruthless character than the Giovanni.
Ernst Stavro Blofeld is a fictional character from the popular James Bond series. He is what is known as both a supervillian and an archenemy. Though I am personally not a fan of James Bond, I did find it interesting when Bulbapedia mentioned that Giovanni may have been based off of this character. In the early films this character had only his lower body portrayed and was seen sitting or stroking his white cat. This most likely heavily influenced Giovanni in the anime in his role as being the mysterious enemy. Though there are many distinct differences between Blofeld and Giovanni, but in other mediums, Giovanni is portrayed just as ruthless.
If you're a child of the late 80's and early 90's you might remember Dr. Claw from the animated cartoon Inspector Gadget. When thinking about Giovanni's doppelgangers, Dr. Claw immediately came to mind. He is a character, the same as Blofeld (maybe perhaps even based on Blofeld himself), who is seen only ever petting his beloved kitty and talking to his minions through his little television screen. He is menacing and enigmatic, traits that are closely linked with Giovanni. He even runs his own underground organization but is also the "archenemy" character, where he will never rest until he defeats the hero. A trait that Giovanni lacks.
When you think Mobsters, you have to think Robert DeNiro! This man has probably been in almost every Mobster movie I have seen in my lifetime, some include (but are not limited to): The Goodfellas, Analyze That, A Bronx Tale, and The Untouchables. He was even a Mobster shark in Shark Tale! If Pokemon was made into a liveaction movie, there is no doubt in my mind that this man would be cast to play the role of Giovanni. In this image, he even seems to have a similar hair style and suit. Giovanni may have even been partially based on this actor.