Juvia is considered a main supporting protagonists in the series. She is formerly a S-Class Mage of the Phantom Lord Guild. Here are the basic stats available on Juvia Lockser.
Name: Juvia Lockser* (ジュビア・ロクサー)
Nicknames: Ameonna, Phantom Girl, Juvia of the Great Sea
Hair: Bright Blue
Eyes: Dark Blue
Likes: Gray Fullbuster
Guild: Fairy Tail, Phantom Lord (former)
Mark Location: Left Thigh (Dark Blue)
Magic: Water Magic, Unison Raid
Affiliations: Gajeel Redfox, Team Natsu, Team Fairy Tail B
Debut: Episode 21 (anime), Chapter 48 (manga)
Voice Actress: Nakahara Mai, Brina Palencia
*In some translations, I've seen her last named spelt "Loxar".