Known for his pro-West stance, Liu has long advocated the need to integrate the Western philosophy and political practices with the Chinese system. In a 2004 article he supported American practices and praised President George W Bush for his 'war on terror' and US military action against 'Islamic world hatred'. By trade a writer, Liu has published many papers criticising China's government, culture, and systems. In 2008, he co-authored Charter 08, mirroring the Czechoslovakia Charter 77. Charter 08 features 19 specific demands, including amending the constitution, guarantee of human rights, free market, protection of environment and independent judiciary. He was detained on December 8, 2008 for co-writing Charter 08. On December 25, 2009, he was sentenced to 11 years' jail and two years' deprivation of political rights. On October 8, 2010, Liu won the Peace Prize. His wife, Liu Xia, was put under house arrest and prevented from collecting it on his behalf.

Zhao Lianhai

Zhao Lianhai is a former food safety worker, who rose to public attention after starting a website aimed at uniting and informing the many parents of jiashibaobao, or kidney stone babies. The babies all developed kidney stones and suffered other kidney damage after consuming powdered milk containing the industrial chemical melamine. This by-product of plastic was added as a 'filler' to make the milk appear to have a higher protein content. The milk power, sold tax-free to parents, was made by Sanlu, a state-owned dairy company. Zhao, whose baby son was among those poisoned, demanded further testing and the prosecution of those involved in the scandal. Although the milk powder was recalled in late 2008, kidney stones continue to be found in children that consumed this milk. Zhao's website, jiashibaobao.org, claimed there were reports of children being told they had no kidney stones after being given free check-ups, only to discover that many were suffering from stones after paying for full mainland examinations or having tests carried out in Hong Kong.

Zhao's website was shut down by the government and also organised a vigil for harmed children at his home. He was arrested in November 2009. On November 10, 2010, he was convicted of creating a disturbance and sentenced to 21/2years' jail. He was released on medical parole in January after a huge public outcry. He criticised Ai Weiwei's arrest in April 2011, Zhou was detained by police, who threatened him with jail for breaching parole by talking to media.

Tan Zuoren

Tan Zuoren, an environmentalist and writer, set up the infrastructure for the 5.12 Student Archive, a project that sought to provide an independent record listing the number and names of all the people who died as a result of poorly built schools collapsing following the Sichuan earthquake on May 12, 2008. At least 5,000 students are said to have died when their schools collapsed. Widespread corruption meant many schools had been forced to run on only 55per cent of their official budgets. The term, 'tofu dregs construction', is often used to describe these buildings as they were just as unsafe as if they had been made from tofu scraps.

Instead of punishing those involved in the shoddy construction, Sichuan's government tried to pay off parents to keep them quiet. Death tolls were largely underreported, leading Tan to arrange his independent investigation. He was detained on March 28, 2010 and charged with inciting subversion of state power and defaming the government. But instead of being prosecuted for his actions over the Sichuan earthquake, he was tried over a few e-mail comments he had written about the Tiananmen Square crackdown. Hong Kong media was harassed during the trial, while defence witnesses were refused entry to the courthouse. Ai Weiwei, who came to Chengdu to testify on Tan's behalf, was beaten up and detained by the police until Tan's trial was over. On February 9, Tan was jailed for five years. He is due to be released on March 27, 2014.

Ni Yulan

Ni Yulan is a Beijing-based lawyer who spoke out against forced evictions of citizens whose homes were in the way of plans for a new, shiny Beijing before the 2008 Olympic Games. The Geneva-based group, Centre on Housing Rights and Evictions, claims about 1.5 million people were displaced because of the Olympics.

First arrested in 2002, Ni was so badly beaten by police that she has permanently lost the use of her legs. She was released after a year, but came to the public's attention again when she fought for her own home, which was under threat of demolition. She was jailed again in 2008, just before the Beijing Games began. While in jail, her home was demolished and she lost everything; her husband was not even allowed to collect any of their personal belongings. After Ni's release in April 2010, police stopped Ni from renting property or staying with friends in Beijing. Instead the couple lived in a tent, donated by supporters, in Beijing Park for 50 days.

Fears that activists were meeting near her tent led police to move Ni and her husband to a cramped hotel room last June. Police also cut the electricity and water supplies to their room in an attempt to force the couple to leave the city. Ni refused to leave until she had written court permission, which would prevent her being regarded as a 'runaway' and rearrested, and allowed to remain active. However, Ni and her husband were detained once again last April 7, together with dissident artist Ai Weiwei and 52 other people.

Chen Guangcheng

Chen Guangcheng, 39, a self-taught 'barefoot' lawyer, was blinded by sickness as a child. But he later took enough law classes to get a grasp of the legal system. In 2005, officials in Linyi Prefecture, in Shangdong Province , carried out harsh and brutal methods to impose the 'one-child' policy. This included forcing thousands of women to undergo sterilisation and late-term abortions - sometimes only a few days before the babies were due - to meet rules that restrict most couples to one child in cities. Asked by the women to give them advice, Chen was labelled an activist when he tried to spread word of this tragedy by talking to Time magazine. Right after the interview, he was placed under house arrest for more than six months. He then faced a trial in August 2006. His lawyers were barred from entering the courthouse for the trial, which some reports suggest lasted less than two hours. He was jailed for four years and three months. Few, if any officials in Linyi have ever been prosecuted.

He has remained under strict house arrest since his release in September last year, with only his mother allowed to leave their home to get food. In February, he sneaked out a video revealing that he had no access to a phone or computer, could have no visitors, or leave the house, and suffered random acts of harassment from thugs hired by the officials. A letter his wife managed to sneak out revealed that he was badly beaten for leaking this information.

Ai Weiwei

Ai Weiwei was born in Beijing, but grew up in Shihezi, Xinjiang , a remote part of northern China as his parents were sent to a labour camp during the anti-rightist movement of the late 1950s. After studying at the Beijing Film Academy with some of the biggest names in Chinese cinema today, he went to New York to study at Parsons, an art and design school.

He was asked to co-design Beijing's Bird's Nest Olympic Stadium. But he expressed anti-Olympic sentiments that were largely kept away from the media and public.

He was involved in the making of a list of the victims of the 2008 Sichuan earthquake, taking special interest in so-called tofu dregs construction schools, which collapsed as the result of shoddy construction. Following this tragedy, he created an exhibition known as Remembering, in which 9,000 school bags were used to make the words, 'She lived happily for seven years', in Chinese, echoing the words of a mother who had lost her daughter in the tragedy.

Yet in November 2010, not even his international status could protect him. He was placed under house arrest and then, on April 3, 2011, detained for 'tax evasion' just before catching a flight to Hong Kong. After his arrest, people around the world spoke out against his imprisonment and demanded his release. In Hong Kong, examples of spray-painted street art cropped up, featuring Ai's iconic hairy face and the words, 'Who's afraid of Ai Weiwei', on government buildings. He was released on June 22. He described his detention 'hellish'.

TIMELINE

1996

October 8 Liu Xiaobo is arrested for co-writing a paper on the Taiwan issue.

2002

Beijing wins right to host the 2008 Olympic Games. Preparations, such as forced evictions, begin

Lawyer Ni Yulan is arrested for her protests against forced evictions and beaten until lame. She is sentenced to prison for one year.

2003

Ni is released from jail.

2005

Shangdong's harsh enforcement of the one-child policy prompts Chen Guangcheng to speak up.

2006

Chen is jailed following a short trial.

2008

May Sichuan earthquake occurs

July, Milk Scandal becomes public

Ni is arrested again when defending her own home against demolition.

Charter 08 is written

2009

Liu is arrested for his involvement in Charter 08.

November 10 Zhou Lianhai sentenced

2010

Ni released from jail

March 28 Tan Zouren is arrested for May 12 Student Archives.

June 16 Ni moved by police from her tent in Beijing Park to a hotel room.

September 8 Chen is released and placed under house arrest.

October 8 Liu wins the Nobel Prize.

2011

January Zhao is given medical parole.

February 9 Tan Zuoren is sentenced.

February A video detailing Chen's strict house arrest is leaked.

April 3 Ai Weiwei is arrested for tax evasion.

April 7 Ni and her husband are both arrested.