Who is Yakamoto?

Let me talk about movies again...
A person named 'Yakamoto' often appears on Hollywood or UK movies. This IMDB search result is not enough because I heard the name on other movies and TV shows like Minority Report and Monty Python. I know Yakamoto is one of the sounds-like-Japanese surname which is frequently used, but actually, there is no one named 'Yakamoto' in Japan.
I heard that the first appearance of a Yakamoto person might be on the 1950s British radio program 'The Goon Show'. Mr. Yakamoto seems to had been portrayed as various stereotype Japanese morons on the show. I don't know the detail, though.

Then, if you are a movie writer (or any kind of fiction writer) and you need a reality for your work, you would rather name your Japanese characters as follows.

SATO, SUZUKI, TAKAHASHI, TANAKA, WATANABE, YAMAMOTO

These are the top 6 of most popular surnames in Japan. As for the first name, HIROSHI, TAKASHI, AKIRA are men's and KEIKO, YOSHIKO, YOKO are female's top 3.