Brendan Barber became general secretary of the TUC in June 2003, having had a 28-year career as an official in the organisation, including spells as a policy officer and head of media.

Barber has spent 28 years in the union movement

Born on 3 April 1951 in Southport, he attended a grammar school in Crosby before going on to complete a degree at City University, London.

He worked his way up through the TUC becoming deputy general secretary in 1993, gaining the top job a decade later.

As head of the unions' umbrella organisation, Barber plays a key role in trying to ensure union priorities remain high on the government's agenda.

He goes into this year's congress warning of troubles for Gordon Brown over the public sector pay settlement.

Barber is married with two daughters and lives in north London.

Unite, the UK's biggest union with about two million members, was formed earlier this year by the merger of the Transport and General Workers Union and Amicus. It currently has two joint general secretaries.

Tony Woodley began his career working at Vauxhall's Ellesmere Port factory in 1967 when he was 19.

Woodley used to work for Vauxhall in Ellesmere Port

Dad George was then full-time works convenor at the plant and his son was soon working his way up the union hierarchy first in the National Union of Vehicle Builders, which later became part of the Transport and General Workers Union.

He was elected as T&G general secretary in 2003 and immediately issued a call to his colleagues to end union in-fighting and build a stronger force for economic change.

As a virtual unknown Derek Simpson quickly developed a certain notoriety after he won control of Amicus.

Simpson has married the same woman twice

It was partly because he was a former communist, who described himself as a lieutenant of the left, and partly because he had succeeding in ousting the man dubbed Tony Blair's favourite trade unionist - Sir Ken Jackson.

He left school at 15 to take a up an apprenticeship in a local Sheffield engineering firm and he quickly became involved in union work rising through the ranks.

Since then he has attained an Open University degree in computing and mathematics and become the leader of one of the biggest unions.

He and Mr Woodley have pushed for Unite to merge with other unions in countries such as the US, Canada and Germany.

Simpson is a father of three who shortly after landing the union's top job reunited with his ex-wife after 20 years apart.

Prentis: Highly critical of Gordon Brown's Private Finance Initiative

Dave Prentis has led the union - the UK's second largest - since 2001. Born and brought up in Leeds, he went to the University of London before going on to do a masters at Warwick in industrial relations. Although he is a Labour Party member, he has been critical of many aspects of the government's policy including the use of private cash to fund schemes in the public sector.

Before becoming Unison's boss he was deputy general secretary from the union's creation in 1993.

Bob Crow leads the Rail, Maritime and Transport Union which is not one the larger trade unions - its membership is around 75,000 - but he is probably one the UK's best known general secretaries.

Bob Crow is not known for a fear of confrontation

He represents many of the UK's rail workers and many employees on London Underground and is not known to walk away from a fight.

Millwall-supporting Crow was born in 1961 and spent his early days working on the Tube.

A former communist, he professes admiration for Arthur Scargill and for Chairman Mao, and he began his own climb up the ranks of the RMT in 1983, succeeding the late Jimmy Knapp as boss in 2002.

He has said: "I'm not one of those union officials who continually say they regret the inconvenience caused by industrial action. You cannot have a dispute without inconvenience to the travelling public."

The RMT been in the headlines recently because of a strike by Tube workers over job security and pensions, which brought most of the network to a standstill.

Crow is married with two daughters and a son.

Billy Hayes has led the 300,000-member Communication Workers Union since 2001 and describes himself as a "critical supporter" of the Labour government.

Billy Hayes began work as a postman

Married with two young children, Hayes began his career as a postman, joining the union before beginning the climb up to his current job.

The Liverpudlian has in the past been branded a member of the "awkward squad" of left-wing union members - a charge he denies.

A Beatles and Bob Dylan fan, Hayes has been a vocal opponent of any plans to privatise the Royal Mail.

CWU members have held strikes recently after rejecting a 2.5% pay deal and postal service modernisation proposals, which the union says could threaten 40,000 jobs.

As the leader of the 320,000-member Public and Commercial Services Union, Mark Serwotka has been at the forefront of resistance to thousands of job cuts in the civil service.

Serwotka is fighting big job cuts in the civil service

For years Serwotka was a benefits officer before climbing the union ranks to become Public and Commercial Services Union general secretary in February 2001. He was re-elected last year.

A left-winger whose past political associations have included the Trotskyite Socialist Organiser and the Socialist Alliance, he has voiced some support for George Galloway's Respect party.

Married with two children, he began his union career at about the same time as his first job - at 16.

Chris Keates has led the 236,000-strong National Association of Schoolmasters and Women Teachers since 2004.

A graduate in archaeology from Leicester University, she taught at two Birmingham comprehensives for 20 years from 1974 to 1994. She then became an advisory teacher in the Birmingham local education authority's central support services.

Keates: Became general secretary in 2004

Keates held a number of elected roles within the NASUWT, including local negotiating secretary for Birmingham and National Executive Member for the West Midlands, prior to joining the staff of the union in 1998 when she was appointed an assistant general secretary with responsibility for co-ordinating the development and implementation of union policy.

Keates describes her politics as private but she has not been afraid of speaking out when she feels the government is getting things wrong.

Mr Kenny began life working in a brewery

Paul Kenny started work at 15, first at Fuller's Brewery in Hammersmith and then as an apprentice gas fitter.

He became active in his local union when became a park keeper in Hammersmith becoming a full-time official in 1979.

He has said his motivation was a fierce opposition to injustice at work, and belief that he could make a difference.

Steve Sinnott became head of the National Union of Teachers in 2004, having served a decade as deputy general secretary.

Mr Sinnott used to be a teacher in Merseyside

A Liverpudlian who began teaching in 1975 at a Toxteth comprehensive, Sinnott worked his way up the union to his current job and is seen as a moderate.

He said his job as general secretary was "one of the most important in education".

Mr Sinnott has a degree in social sciences from the former Middlesex Polytechnic, and trained as a teacher at Edge Hill College in Ormskirk.