Before Gearbox Software came up the look and personalities of Borderlands characters Roland, Mordecai, and Lilith, they devised the basic archetype of each class, with each originally represented in art as a blockhead, a conehead and a spherehead.
Borderlands franchise director Matt Armstrong and lead character designer Jonathan Hemingway were at SXSW offering a behind the scenes look at the early stages of how the in-game team came together. The designers knew they wanted a Doom-style shooter guy, a stealthy Metal Gear-type expert, and a James Bond-style gadget killer. The rough concept art for each class was represented by a sketch that had a 3D shape as a head. After some thought, they realized a play-style was missing, and Brick was eventually added as a tank-type class.
The duo also detailed the original gimmicky UI interface for the skill trees, including Brick's tree involving a series of beakers and IV bags meant to reflect his drug-induced roid-rage abilities. Those were eventually scraped, however, in favor of the three-skill-tree system.
To see more of Borderlands' design process, see the slides over at Joystiq