#3 D'Lo Brown
D'Lo Brown was one of the most athletic, gifted, and skilled in ring performers of the Attitude Era. Unfortunately, the Attitude Era was more about the appeal of characters and interview skills than technical wrestling ability.
In spite of being thought of as 'boring' by the WWE management, D'Lo managed to become a dual champion in WWE, capturing both the European and Intercontinental championships and holding both simultaneously.
A tragedy marred D'Lo Brown's career during this point of his life, as he accidentally dropped Darren "Droz" Drozdov on his head during a failed running powerbomb attempt. Droz would be paralyzed from the chest down as a result of the accident.
D'Lo's WWE career eventually came to an end, but he did work for TNA wrestling as well as All Japan Wrestling.
Why no one remembers him: It's all about the timing. If D'Lo Brown were in his prime and joined NXT today, he would be a major star on that brand. Unfortunately, he just wasn't the right fit for the Attitude Era.