Hard-working midfielder signed by Tony Adams from West Ham in January 2009.
Mullins played a key role in keeping Pompey in the Premier League in his first season and was then used in a variety of positions under Avram Grant, filling in full-back on several occasions.
Under Steve Cotterill, Mullins has been a mainstay in central midfield and netted his first Blues goal in the win over Bristol City early in the 2010-11 campaign.
Mullins started his career at Crystal Palace, where he spent seven years after coming through the ranks at Selhurst Park.
He then moved to Upton Park for £800,000, where he went on to make 212 appearances before Gianfranco Zola allowed him to move.
After a difficult start to his Blues career that saw supporters slow to take to him, the midfielder is now regarded as a vital player.
Former clubs: West Ham, Crystal Palace
Date of birth: 27/03/79
Height: 5ft 11in