This character is named differently depending on the translator. Jellal is a literal translation; Gerard is a romanisation, completing the sounds that the Japanese language can't sound. His surname though, is portuguese.
Jellal is introduced under the alias of Siegrain, a young member of the Magic Council and can be considered the main antagonist of the series. His design is the same as that of Rave Master's Sieg Hart, Hiro Mashima's previous work, as a form of fan service. With his "underling" Ultear he typically disagrees with the rest of the Council, typically by showing leniency to Fairy Tail.