Profile: Clarke Carlisle - No ordinary footballer
In his playing days he was a good defender.
He spent most of his career in the lower divisions but did have spells in the Premier League with Burnley and Watford while he also represented England at Under-21 level.
But it is off the pitch that he has really stood out.
In 2002 he was named Britain's Brainiest Footballer after appearing on a TV quiz, while he has also been a contestant on Countdown and a panellist on Question Time.
In recent years, the 36-year-old has been a major figure in football politics, serving as chairman of the players' union, the Professional Footballers' Association (between 2010 and 2013) and also as an ambassador for anti-discrimination organisation Kick It Out.
It has seemed a natural fit for someone who achieved 10 A grades at GCSE, studied maths and politics at A-Level while out injured and also has a degree in Professional Sports Writing and Broadcasting from Staffordshire University.
He also began a media career before his retirement from professional football in 2013, working as a pundit and presenting TV documentaries on racism and mental health issues in football.
The latter was a subject particularly close to his heart, having previously opened up about past struggles with depression and alcoholism.
These included a suicide attempt in 2001, triggered by a potentially career-threatening knee injury.
Carlisle, also a devout Christian, was born in Preston and followed his father Mervin - a semi-professional with Morecambe and Southport - into football.
He began his career with Blackpool before moving to QPR.
It was while at Loftus Road that he suffered his serious knee injury, a torn cruciate ligament that sidelined him for more than a year-and-a-half.
He moved to Leeds in 2004, after recovering, and then Watford, where injury again struck and limited his involvement in their 2006/07 top-flight campaign to four appearances, although he did play in an FA Cup semi-final.
He got another chance in the Premier League with Burnley in 2009/10, one of three seasons in the Clarets first team before he fell out of favour.
He had spells at Preston, York and Northampton before retiring two years ago.
He has two children with wife Gemma and an elder daughter from a previous relationship.