The leader of neo-Nazi group National Action has been jailed for eight years after he was found guilty of membership of the banned group .
Christopher Lythgoe, 32, from Warrington, was sentenced at the Old Bailey. Another prominent National Action member, Matthew Hankinson, 24, was jailed for six years for membership of the group.
The far-right group was banned by the Home Secretary over its support of the murder of Labour MP Jo Cox, who was shot and stabbed to death in 2016 by neo-Nazi Thomas Mair.
The court was told that Lythgoe had regarded the death of the Batley and Spen MP in her own constituency as a "little victory".
Lythgoe was arrested by police investigating a plot to murder Labour MP Rosie Cooper and a female police officer.
He was also accused of encouraging the murder of the West Lancashire MP, but was found not guilty.
The plot was foiled after whistle-blower Robbie Mullen leaked details of a meeting between members to campaigner group Hope Not Hate in July last year.
Jack Renshaw, 23, pleaded guilty to preparing to engage in an act of terrorism by buying a knife to kill the politician and threatening a police officer.
Renshaw, from Skelmersdale in Lancashire, has also been convicted of inciting racial hatred in speeches in 2016.
He was accused of being a member of National Action, but the jury failed to reach a verdict.
They also failed to reach verdicts on Andrew Clarke, 33, and Michal Trubini, 35.
Garron Helm, 24, was acquitted of the same charge.
Head of Investigations for Counter Terrorism Policing in the North West, detective superintendent Will Chatterton, said: "Today's result has enabled the spotlight to be shone on the sickening activities of the banned extreme right-wing organisation National Action.
"During the trial, one of those jailed today stood before the court and openly denied the Holocaust had taken place - an unimaginably horrific event that resulted in the murder of millions of Jews at the hands of the Nazi regime.
"Today's result is a body blow to extreme right-wing organisations such as National Action.
"It sends out a clear message that counter-terrorism officers and partner agencies will rigorously identify and investigate any violently extreme individual or group who seek to bring a reign of terror to our shores."
Mr Justice Jay said the group had a "truly evil and dystopian vision" to create a race war and had been kept going by Lythgoe's obsessive determination.
He said that Lythgoe "did nothing to stop or discourage" the plot to kill Ms Cooper.
The judge added that while its numbers were too small to achieve its true aims, there was a risk that the group's ideology could have inspired terror attacks.
He described Lythgoe as a "fully-fledged neo-Nazi complete with deep-seated racism and anti-Semitism".
Ms Cooper, who sat in court as the men were jailed, said in a statement: "I think it's awful that any public servant - teacher, nurse, doctor, police, MP - should be targeted and threatened with violence simply because of the job they do.
"To that end, I'd like to thank Robbie Mullen, whose information saved my life.
National Action is the first extreme right-wing group to be banned by the government since World War Two and had up to 100 members at its height.
The court heard that the group planned to "wipe out" non-white people "by any means necessary".
In his sentencing, Mr Justice Jay said that National Action meetings, under Lythgoe's leadership had continued on a "modest" scale after the group was banned by then-Home Secretary Amber Rudd.