Marine David Charles Hart, 23, of 40 Commando, died on Thursday after he was caught in a blast while on foot patrol in the Sangin District of Helmand Province.
His parents Dilys and Chris Hart, from Upper Poppleton, North Yorkshire, said: "David loved his family, his girlfriend and friends, many that he has known since early age.
"Throughout his life David showed the qualities of the Commando Spirit, he had a great personality and was a friend to everyone.
"His cheerfulness, his sense of humour and of course his smile will be sorely missed, but never forgotten.
"We are immensely proud, as he was, of his achievements."
His sister Sarah Hart said: "Dave was the best brother I could ever have wished for.
"He was caring, funny, had an infamous cheeky grin and would always be there for you.
"I am so proud to have been his sister, and of his chosen career as a Royal Marines Commando.
"He truly loved his job and relished the challenges he was facing on a daily basis.
"Dave, I will miss you so much. You were so brave and I will always remember you as a true hero."
The Ministry of Defence said Marine Hart joined recruit training in February 2009 and stood out as one of the top recruits.
He passed out for duty as a Royal Marines Commando on October 16 2009 and was awarded The Commando Medal.
The medal is only given to those who show an outstanding degree of courage, unselfishness, determination and cheerfulness under adversity, qualities which the Royal Navy says defines "the Commando Spirit".
Marine Hart was drafted to 40 Commando Royal Marines, joining Charlie Company, and was deployed to Afghanistan in April.
He was killed the day before he turned 24.
Lieutenant Colonel Paul James, Commanding Officer 40 Commando Group, Combined Force Sangin, described Marine Hart as "fiercely courageous".
"Marine Dave Hart was magnificent, both in personality and in profession," he said.
"Diligent, loyal, utterly dedicated and completely selfless, he was a perfect Commando.
"He had a resolute but compassionate manner that everyone admired; he thrived in adversity and inspired others to do the same.
"He was tragically killed on the eve of his 24th birthday, with a bright career ahead of him, but he died doing the job he loved and amongst friends who will love him forever."
Major Ed Moorhouse, Officer Commanding Charlie Company, 40 Commando Royal Marines, said Marine Hart was "universally popular".
"There was not an ounce of malice in Dave, he was always cheerful, always upbeat and a friend to everyone.
"This wholesome, compassionate and thoughtful man was fiercely proud of his profession, of his Corps, Charlie Company and the Band of Brothers who he fought alongside."
Major Moorhouse added: "I am greatly saddened that a journey that had such rich and abundant potential has ended in such tragic suddenness. He was a man with the Corps at his feet."
Marine Hart was selected to become part of the newly formed Police Mentoring Team, training the Afghan National Police.
Captain Dom Rogers, Officer Commanding, Police Mentoring Troop, said: "Marine Dave Hart was one of the very best young marines I had under command, a man who displayed all of the attributes that I could have asked for as his Troop Commander.
"He joined the Police Mentoring Troop when it was formed in January, prior to deploying to Afghanistan.
"Demonstrating early on, that although only recently out of training he was more than capable of standing toe to toe with his more senior counterparts on what is a difficult tour of duty.
"Since deploying to Afghanistan, to mentor the Afghan National Police in Sangin, Dave Hart grew in stature as a Royal Marines Commando.
"He was a keen, enthusiastic and lively member of the Troop. He maintained an absolute dedication to his comrades and a professionalism that belied his relative inexperience."
Captain Rogers said the mentoring role required patience and moral courage.
"Dave Hart had these qualities in abundance; he never failed to rise to the challenge with good humour, which endeared him not only to the rest of the Troop but also the Afghan Policemen, who he worked alongside."
He said Marine Hart was also a formidable athlete who had helped to create a Troop gym out of vehicle tyres and other objects lying around the base.
Sergeant Damian O'Sullivan, Troop Sergeant, Police Mentoring Troop, said he struggled to find the words to describe Marine Hart and explain the impact he had on everyone who met him.
Sergeant O'Sullivan described his "utter lust for life, his love of his family, his girlfriend Sarah and of course his friends".
"I have tried to find just one word that described him; in my eyes the only word that comes to mind is, indomitable. He refused to be beaten by any circumstance and always displayed the Commando quality of cheerfulness in adversity.
"Dave had the ability to smile which would reassure you that things could not always be that bad."
He described him as "an outstanding man to work alongside".
Marine Nick Warnock, Police Mentoring Troop, said: "His 'no job too tough' perspective and 'you can't beat me' smile were his trademark features."
Marine "Ollie" Oliver, Police Mentoring Troop said: "Dave and I had many conversations about the dangers of our job and in these conversations we did talk about the potential of one of us passing.
"In these conversations he said that if this were to occur he couldn't complain and that he had loved life and up until that time he had a brilliant one.
"His greatest fear was leaving his family, girlfriend, friends and loved ones distraught and upset, but in talking about this he wanted us to celebrate his life and remember the good times."
Marine Ryan Johnson, Police Mentoring Troop said: "He could lift everyone's mood with just one witty comment, and the flash of a cheeky grin. I envied him, in the nicest of ways, all of the time I knew him. He had it all, good looks, a charming personality, great physical and mental strength, an indomitable spirit and a career that he loved.
"My thoughts are with his girlfriend Sarah, who he always talked about with a great sense of affection and true love, and his family and friends all of whom he cared much about."
Corporal "Bob" Roberts, Section Commander, Police Mentoring Troop said: "He was without doubt the most optimistic and positive person I have ever met, and ever likely to."
Cpl Roberts said Marine Hart spoke of his beloved York and his longing for "a cold pint of milk and a curry" when he went home.
Secretary of State for Defence Dr Liam Fox said: "Marine David Charles Hart has given his life bringing stability to an area vital to our mission in Afghanistan.
"An exceptional Marine who will be greatly missed by his colleagues in 40 Commando, I extend my deepest sympathies to his family and loved ones during this sad time."
Marine Hart was the 101st member of UK forces killed in the Sangin region, which Britain will hand over to the US Marines at the end of this year.
Nearly a third of the 314 British deaths in Afghanistan since 2001 have happened in Sangin, currently home to the Royal Marines and supporting units of 40 Commando Battle Group.
Defence Secretary Liam Fox confirmed on Wednesday that UK forces would be withdrawn from the district in the autumn.
A US Marines battle group will be moved from Nimruz Province to take control of the area.
The handover will leave the British military effort concentrated in central Helmand, which covers a relatively small area but is home to a third of the province's population.