Greedo is perhaps best known for shooting first in the Episode IV Special Edition, but the controversy doesn't end there. His recent appearance in The Clone Wars raised many questions about Greedo's backstory and role in Star Wars. There are a few parts of his backstory, however, that seem to still be accurate.
Biography
Greedo was a Rodian, part of a reptilian humanoid species from the planet Rodia. He was born around 44 BBY and grew up on the desert planet Tatooine. Not much is known of his early life, except that in 32 BBY he accused Anakin Skywalker of cheating in the Boonta Eve Podrace.
At some point, Greedo followed in his father's footsteps and became a bounty hunter. He primarily worked on Tatooine for Jabba the Hutt. During the Clone Wars, he helped kidnap the children of a Pantoran diplomat, which was part of a Separatist conspiracy to influence the planet's politics.
Greedo was never known for his skill or success as a bounty hunter. He died in 0 ABY while attempting to recover the money Han Solo owed Jabba the Hutt. Greedo attempted to shoot Han, but somehow managed to miss at point-blank range just before Han shot him under the table.
Controversy
The appearance of Greedo in The Phantom Menace contradicted several parts of Greedo's backstory, possibly including the maximum age of his species. As a result, Expanded Universe authors invented another character, Greedo the Elder, who appeared in Episode I and later became Greedo's father.
When Greedo appeared in The Clone Wars episode "Sphere of Influence," however, another retcon became necessary to explain how Greedo could be an adult bounty hunter if his father was a child ten years earlier. The issues with Greedo's backstory, and that of his father, have not yet been resolved.
Behind the Scenes
Two Greedo masks were produced for A New Hope. The first was not very expressive, and so Lucas shot close-ups using a second mask. The two actors who portrayed Greedo were Paul Blake and Maria De Aragon. Tom Kenny voiced Greedo in Star Wars: The Clone Wars.
The language Greedo speaks in A New Hope is Quechua, a native South American language. The in-universe language is Huttese, one of the most widely-spoken languages in the Star Wars galaxy.