Barry, 35, whose 609 appearances in the Premier League is a total exceeded only by Ryan Giggs, has extended his contract to June 2018. Baines, 32, who is in his 10th season at Everton having made 351 appearances for the Club, extended his contract to June 2019 and Holgate, who was handed his Premier League debut by Koeman in the 1-1 draw against Tottenham on the opening day of the season, has extended his contract to June 2021.
Everton manager Koeman said: “With Leighton, his attitude is always perfect. He likes to work hard, he likes to learn, he is a technical player with a good view of the game and I’m really happy to have him in the team this season and also for the longer term.
“Offensively, he’s a strong player who can cross the ball well and he has that cleverness in the game and in the moment, a quality that’s not in every player.
“He’s one of the experienced players in our team and what you like to have in your team is a balance in ages in the group. Players like Leighton, Phil Jagielka and Gareth Barry are leaders in our dressing room and on the pitch. For younger players, they are a little bit like teachers. They have that experience and young players need to listen to them for they will learn.
“Like Leighton, Gareth Barry is a clever player on the pitch. Only Ryan Giggs has played more games in the Premier League and let’s hope he will smash every record. He’s a quiet person but a strong character. He knows what he can and can’t do.
“He is a key player for the team. Of course, sometimes you need to protect older players, with all due respect. Gareth is 35 but he is still so important for the team and I’m very happy he has extended his contract.
“Mason is one of the big talents at the Club. Of course, he started playing this season and did a great job. He can play out of different positions in the team defensively. He was really comfortable when he got his chance in the team. He showed strengths with the football and strengths in defending. He’s the future for the Club and other young players like him.
"For young players it's difficult to come into the first team but we are really happy that at Everton we have a lot of young players who can make that step." - Ronald Koeman
Barry said: “The new manager has come in and given me a new lease of life. It’s someone else to try and impress and new tactics to take on board. It’s really helped my game and I’m looking forward to taking that on and enjoying this season, which is hopefully a successful one.
“They say you can’t buy experience and, for me, it feels so much easier going out on the pitch knowing what I know. Obviously there’s different sides of the game that are needed, such as energy, but I feel as comfortable on the pitch as I have ever done and a successful team here is something I want to be part of.”
Baines said: “The majority of my career I’ve spent here at Everton and it’s something that I hope will continue even beyond these next few years. I hope I’m always affiliated with Everton. It’s a huge honour for me to play for the Club for as long as I have and I’m very proud to have been here for as long as I have been.
“I’m very lucky as well. You work hard, you look after yourself and you always try to do the right things and the reward for me has been to spend such a long time at such a great club.
"It's an achievement in itself when you think back to being a kid playing football on the streets to becoming a professional footballer - and not just for any club, for a club like this. It's very special." - Leighton BainesHolgate said: “It’s been a bit of a whirlwind this season, to be honest. I wasn’t expecting it but I’m really enjoying it and hopefully there are many more experiences to come. My confidence has grown as I’ve spent more time with the first team. I feel settled now and a proper part of the group.
“Obviously, the lads have helped me a lot and to have two great senior professionals like Jags and Ashley [Williams], who play in the same position as me, is always going to help. I watch things that they do and try to take everything in to improve myself. There’s others as well, players like Seamus who are also helping me. I’m getting a lot of advice from some very good senior players.
“The manager has been really good with me as well. Obviously, it was great to get a chance under him so early on. I’ve got all of these people around me, helping me along the way and I just want to continue to learn and grow as a player and do all I can for the Club.”