Originally, Nintendo was a playing card company. Among the licenses they held was Popeye the Sailor, which was owned by King Features.
In 1981, Nintendo made one of those cheap pocket games starring Popeye, and planned to release a more elaborate one for the arcades. A first-time designer named Shigeru Miyamoto was assigned to the project and began sketching game concepts involving the classic Popeye/Olive Oyl/Bluto threesome.
After one of those concepts was approved, Miyamoto found out that King Features had denied Nintendo the rights to bring Popeye to the arcades. The characters were suddenly off limits to Nintendo, but Miyamoto went ahead with the game anyway - keeping the threesome, but arbitrarily replacing Popeye with a plumber, Olive with a princess and Bluto with an ape.