Hughes was carried off on a stretcher at the Sydney Cricket Ground after he was struck on the top of the neck by a short-pitched delivery from Sean Abbott, 22, during a Sheffield Shield game against New South Wales on Tuesday.
Cricket Australia CEO James Sutherland has paid this tribute to Hughes, describing him as a "hero to kids around the nation".
Australia cricket team coach Darren Lehmann, via Twitter: "RIP you little champ, we are all going to miss you. Love, prayers to all the Hughes family xxxx."
Cricket Australia on Twitter: "The strength of the cricket family is more important than ever on this incredibly sad day. Please keep Sean Abbott in your thoughts."
Australian Prime Minister Tony Abbott: "Phillip Hughes was a young man living out his dreams. For a young life to be cut short playing our national game seems a shocking aberration. He was loved, admired and respected by his team-mates and by legions of cricket fans."
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Former Australian Prime Minister John Howard: "It's a terrible accident and it should be seen in that light, it's nobody's fault. It's a terrible accident and it's a terrible loss to his poor family and I send my prayers and thoughts to them."
England batsman Nick Compton, who played with Hughes in Sydney and shared a house with him in London in 2009: "He was a very, very close friend of mine. He was a cheeky, funny, positive guy. Looking back, I feel like he's made the most of his 25 years and it breaks my heart to think of a guy who I certainly thought would go down in the record books as one of the better run-scorers in Australian cricket."
The England team released a statement on Twitter, saying: "Our deepest sympathies go out to Phil Hughes' family, friends and teammates at this incredibly sad time. Phil was admired and respected by all he played with and against and will never be forgotten by the cricket community."
England bowler Stuart Broad on Twitter: "Just can't believe it, heartbreaking stuff. RIP Phil Hughes."
England bowler Jimmy Anderson on Twitter: "Can't quite believe the news. Devastating. My thoughts go out to Phil Hughes' family and friends. Thoughts also with Sean Abbott."
England batsman Joe Root on Twitter: "Awful to wake up to the news of Phil Hughes. Tragic day for the sport. Thoughts go out to those close to him."
Former England batsman Kevin Pietersen on Twitter: "NO NO NO NO NO. RIP, Hughsey #63notout"
Lord's Ground on Twitter: "Absolutely devastated to wake to the news of Phil Hughes' death. The MCC Flag at Lord's will be lowered in his memory."
MCC president David Morgan: "Cricket can be a dangerous sport, but for a talented young man to lose his life playing the game he loved is beyond most people's comprehension."
ECB chairman Giles Clarke: "He was an extremely popular and hugely respected cricketer in England and Wales not only as a successful tourist with various Australian teams but also as a wonderfully talented county player with Hampshire, Middlesex and Worcestershire."
Former England captain Michael Vaughan on Twitter: "Just far too young. He was only doing the job he loved and was brilliant at it."
Former England captain Ian Botham on Twitter: "A very sad day for the world of cricket. So sorry for Phillip Hughes and his family. Spare a thought for Sean Abbott."
Former England captain Andrew Strauss speaking to Sky Sports News: "The most sickening aspect of all of this is that he was a guy in the best years of his life and that was extinguished out of the blue.
"He was only 25 and to have achieved what he did in such a short period of time was extraordinary. He was modifying his game all the time as well.
"It is a tragedy that he is gone in terms of cricket, but that pales into insignificance when compared to what his friends and family are going through."
Former England captain Mike Gatting: "The reaction just shows how much the guy made an impact on people around the world. It was a freak accident that has taken someone at the prime of his career and has so much more to give."
Former England bowler Dominic Cork, who played alongside Hughes at Hampshire: "I will remember him as a very fine young cricketer trying to make his way back into the Australia side.
"Sharing the same dressing room as him, he was a man you would always remember. He always had a cheeky smile on his face, always wanted to be the best and wore that baggy green with such pride.
"We have lost one of the bright hopes who would have been a big success in the game."
Worcestershire director of cricket Steve Rhodes, who coached Hughes during his season with the county side: "He was very humble, good fun and nobody had a bad word to say about him. He spent a lot of time working with the younger players, passing on his knowledge which was great for us."
Hampshire chairman Rod Bransgrove, reflecting on Hughes' spell with his county in 2010: "I cannot begin to comprehend the loss of a talented, ebullient and lovely lad.
"In the Australia dressing room after the international T20 at the Ageas Bowl in 2013, Hughesy said to me that after Shane Warne, Simon Katich, Shane Watson and Michael Clarke he felt like Hampshire's forgotten Aussie.
"I told him then, and I say it again now, you will never be forgotten Hughesy - you are part of our family. Rest in peace buddy."
Former England Test batsman Paul Collingwoodon Twitter: "Cricket has lost a super talented cricketer but most of all a lovely, lovely man. All our thoughts with his family."
The India team currently touring Australia also released a joint statement which read: "The touring Indian team joins the cricketing fraternity across the world in offering condolences to the family of Phillip Hughes, who has departed from our midst. In this moment of grief, we pray that they are bestowed with divine strength to overcome this unfortunate tragedy.
"As fellow cricketers we cherish the memories of playing along with him and deeply respect his contribution to the game of cricket."
Australia batsman David Warner on Instagram: "RIP my little man. You will always be with me when I walk out onto the field. Not just a mate but a loved one to us all big man. Forever in my heart brother for life. Miss you buddy."
Former Australia spinner Shane Warne, speaking to Sky Sports News: "He is very, very humble. He loved the game and wanted to the best player he possibly could. It is just an absolute tragedy.
"It is just so, so sad and horrific We've lost one of the good guys."
Former Australia cricketer Glenn McGrath: "Such terrible news with the passing of Phil Hughes. Our deepest sympathies to his family."
Former Australia fast bowler and Yorkshire first team coach Jason Gillespie, speaking to Sky Sports News: "A lot of the Australia lads will have grown up playing cricket together and it will be a very tough time for them.
"Sean Abbot is a lovely young kid who was just running in and doing his job, bowling balls and it was one of the last things that he would have expected.
"We are really feeling for him right now and everyone who was there."
Australia Test spinner Nathan Lyon: "Today we lost one of the greats. RIP Hughes #408 #willbemissed #loveyamate."
Australia all-rounder Steve Smith via Twitter: "Rest in peace Hughesy. I am really going to miss you. You were one of the great blokes and I will never forget you. #408 will live on forever."
Australia batsman Shaun Marsh via Twitter: "You defined character, courage and most of all laughter, you will be missed by many my friend. RIP"
Former paceman Brett Lee, who also played alongside Hughes in the national team, tweeted a picture of him sat alongside the batsman and said: "No words can describe the loss. RIP."
South Australia team-mate Kane Richardson: "It was an honour to play alongside you at club, state and international level. You were an absolute genius on the field and a loveable lad off it.
"To know that we will never share a changing room again hurts, but I am privileged to know that we did. Every time I pull on one of those caps above I will think of you.
"I don't know how we will go one without you, but we will have to find a way, which is what you always did. Even in your last innings they still couldn't touch you. 63*. RIP Brus, Son, Boss, maaaaaate."
Former News Corporation chief cricket writer Malcolm Conn: "He was a very quiet kid in public, but very cheeky among his team-mates and very well liked, not only in Australian cricket, but around the world.
"He was a short nuggety little fellow, but he had just the biggest, most infectious smile, anyone who got to know him could not fail to be positively affected by his smile and the way he engaged with people."
Australian Olympic cyclist Anna Meares via Twitter: "Sheer shock and sadness at the passing of Phil Hughes. My condolences and thoughts with his loved ones, friends and team-mates."
Australian Olympic swimmer Stephanie Rice via Twitter: "Awful, awful news. What a devastating end to an incredibly talented athlete. My love goes out to everyone who cared and loved for you Phils."
Legendary Indian batsman Sachin Tendulkar on Twitter: "Shocked to hear about Phil. Sad day for cricket. Deepest condolences to family, friends and well wishers. RIP."
Former South Africa fast bowler Shaun Pollock on Twitter:  "Absolutely shocked to hear the news of Phil Hughes passing away. Thoughts and prays are with his family as well as Sean Abbott."
South African cricketer AB de Villiers via Twitter: "Heart broken. A very dark day. You will be missed, Phil Hughes. My prayers and thoughts go out to his family & friends."
South African fast bowler Dale Steyn via Twitter: "Totally saddened by the passing of our cricket brother and friend Phil Hughes. Terrible loss. Deepest condolences to his family."
Sri Lanka cricketer Mahela Jayawardene: "Just heard the worst news possible... our thoughts & prayers are with Phil, his family & friends. RIP Phil Hughes."
Cricketers, politicians and sports people have paid tribute to Australia cricketer Phillip Hughes, 25, who has died two days after being hit by a ball while batting for South Australia in a domestic game.