Hartmut Esslinger takes credit for being one of the first people in Apple to work on the design of the Macintosh in 1980s. In his recent book titled "design forward" he reveals some of the rare concept designs of the early Apple computer and tablets from the 1980s which never went into production.
Apple used Esslinger's company Frogdesign extensively in the 1980s. When Steve Jobs saw the work that Frogdesign was doing for Sony he offered them a 2 million/year contract to open an office in Silicon Valley. Jobs wanted them to create a signature look for the new Macintosh line and together they built the Apple IIc which was introduced in 1984.
Below you can see some of the designs created by Frogdesign for the early Apple computers and tablets. More details at designboom.