The family of Drummer Lee Rigby, who was killed in a terrorist attack in Woolwich, have said he would do "anything for anybody".
The soldier, who was married and had a two-year-old son, was described as a "loving son, husband, father, brother and uncle, and a friend to many".
His colleagues in 2nd Battalion the Royal Regiment of Fusiliers said he was as an "extremely popular and witty soldier" who had a "larger than life personality" and was a passionate, lifelong Manchester United fan.
Witnesses said the 25-year-old was set upon by two men who attacked him with knives and a meat cleaver while shouting the name of "Allah".
They were shot by police and arrested at the scene on suspicion of murder.
Two other people - a 29-year-old man and a 29-year-old woman - were arrested on suspicion of conspiracy to murder, following raids in London and Lincolnshire.
In a statement, Drummer Rigby's family said: "Lee was lovely. He would do anything for anybody. He always looked after his sisters and always protected them. He took a 'big brother' role with everyone.
"All he wanted to do from when he was a little boy was to be in the Army. He wanted to live life and enjoy himself."
Emma O'Reilly, a friend of Drummer Rigby, was on a bus close to the scene of the attack when she saw his name and picture on her phone and realised he had died.
"I was just absolutely shocked," she told Sky News. "It's hard for this to happen to anyone but when you know the person, it makes it even worse."
Heartfelt military tributes to Drummer Rigby, affectionately known as 'Riggers', each ended with the message: "Once a Fusilier, always a Fusilier."
Lieutenant Colonel Jim Taylor, Commanding Officer of the 2nd Fusiliers, described him as a "true warrior" who served with distinction in Afghanistan.
"Drummer Rigby was a dedicated and professional soldier," he said. "He was a real character within the 2nd Fusiliers. Larger than life, he was at the heart of our Corps of Drums."
"Riggers was what every battalion needs," added Warrant Officer Ned Miller, Regimental Sergeant Major of the 2nd Fusiliers. "He was one of the Battalion's great characters - always smiling and always ready to brighten the mood."
Drummer Rigby, from Manchester, served in Afghanistan in 2009 and was also posted to Cyprus and Germany.
His battalion is currently training in Cyprus but he was on attachment to its London headquarters as a recruiter.
Defence Secretary Philip Hammond said everyone had been "shocked and saddened" by Drummer Rigby's death.
"This was a senseless murder of a soldier who has served the Army faithfully in a variety of roles including operational tours in Afghanistan," he said.
"Our thoughts today are with his family and loved ones who are trying to come to terms with this terrible loss."
General Sir David Richards, chief of defence staff, added: "Our first thoughts are with the soldier's family and close friends.
"It's always a tragedy but it's particularly poignant that it happened on the streets of our capital city."
One of the men arrested at the scene has been identified as Michael Adeboloja , a 28-year-old Londoner of Nigerian descent.
He and the other suspect, aged 22, are being held under armed guard at separate hospitals in London.
They were both known to the security services but were assessed by MI5 as not posing a threat requiring "immediate intervention", Government sources said.
Police investigating the attack have been searching a flat in Greenwich and a house in Lincolnshire, believed to be connected to Adeboloja.
One passer-by filmed Adeboloja holding a bloodied meat cleaver and saying: "We must fight them as they fight us. An eye for an eye, a tooth for a tooth."
"I apologise that women have had to witness this today but in our land our women have to see the same," he added. "You people will never be safe. Remove your government, they don't care about you."
Ingrid Loyau-Kenned, a cub scout leader and mother-of-two, recalled the moment she confronted the alleged attackers and warned them: "You are going to lose."
Another witness, identified as James Heneghan, said the soldier had been attacked with kitchen knives like he was "a piece of meat".
"They were hacking at this poor guy, literally," he told LBC radio.
Meanwhile, Prime Minister David Cameron chaired a second emergency meeting of the Government's Cobra committee.
Speaking afterwards, he said: "The people who did this were trying to divide us. They should know something like this will only bring us together and make us stronger.
"One of the best ways of defeating terrorism is to go about our normal lives."
Elsewhere, the Muslim Council of Britain said it had received "reports of hate attacks and abuse faced by mosques and individual Muslims following the inexcusable and criminal murder".
The group called for solidarity between "all our communities, Muslim and non-Muslim".
Riot police had to contain an English Defence League demonstration in Woolwich, while two mosques were attacked.
Geoffrey Ryan, 43, has been charged with two counts of possession of an offensive weapon and one count of affray, after he was allegedly found with a knife outside a mosque in his home town of Braintree, Essex.
He is due to appear before magistrates in Colchester, Essex, on Friday.
:: Police have issued an appeal for anyone who has still or moving images of the incident to email them to their incident room .
They asked anyone sending in images to include their name and contact details, which they said would be treated in the strictest confidence. Alternatively, those with footage can contact the police's anti-terrorist hotline on 0800 789321.