EVERY club that competed in Sky Bet League One last season has now published their retained list.

Dozens of players will become free agents when their contracts expire at the end of this month, with some already sealing moves to pastures new.

But plenty more are yet to sort out their futures, as far as we know, and could represent attractive options to Oxford United on a free transfer.

READ MORE: List of available League One players as clubs publish retained lists

The U’s made good use of the free agent market last summer with the signings of Billy Bodin and Ryan Williams, so they will surely be looking again this year.

United need reinforcements in defence, with Elliott Moore, Luke McNally and club captain John Mousinho the three senior centre backs contracted for next season.

Meanwhile, Sam Long and Steve Seddon are the only full backs in the squad, although Anthony Forde has played there in the past.

With that in mind, here are five defenders released by League One sides at the end of the season who could add something to the U's.

Part two will focus on forward players and comes out later this week.

CHEY DUNKLEY

The centre back is a familiar face to U’s supporters, becoming a fan favourite and winning promotion from Sky Bet League Two during a three-year spell at the club between 2014 and 2017.

Dunkley joined with United near the bottom of the fourth tier, but he has played in League One or higher ever since.

The defender spent three years at Wigan Athletic after leaving the Kassam Stadium in 2017, only to break his leg in what proved his last appearance for the club in February 2020.

Dunkley joined Sheffield Wednesday that summer and did not make his debut until December, with further injuries restricting him to just 36 appearances in two years at Hillsborough.

That could be the main factor in the ‘against’ column for the 30-year-old. There are also other defenders around who are more comfortable playing out from the back.

Having said that, his ability in the air and his infectious character are among the strengths that would be an asset to any League One side.

READ MORE: Sam Baldock signs two-year deal with Oxford United

ETHAN EBANKS-LANDELL

The centre back could have scored against United twice in the last two seasons, only to be denied by wonder saves from Jack Stevens last year and Simon Eastwood this March.

News of Ebanks-Landell’s release by Shrewsbury Town last month was greeted with surprise, which showed his standing in Shropshire.

Indeed, the 29-year-old racked up 125 appearances in his three seasons at Montgomery Waters Meadow – 124 of them starts.

The former Wolves trainee is used to playing in a back three, having done so over the last three seasons, and Karl Robinson has already said that formation will be an option next term.

Ebanks-Landell is not what you would call a ball-playing centre half, but a 3-5-2 would allow him to accentuate his strengths as others drive out from defence.

READ MORE: Oxford United extend deadline for season-ticket renewals

CHRIS GUNTER

The Welshman turns his attention back to his own future once he has finished celebrating World Cup qualification with Sunday’s 1-0 win over Ukraine.

Gunter was released by Charlton Athletic last month, ending a two-year spell in south London where he made 58 appearances.

At 32, the defender has bags of experience: he is Wales’ most-capped player and has spent most of his career in the Championship.

Gunter is a right back by trade and has played wing back for his country at a major tournament so he knows the position - another positive for a side looking to play 3-5-2.

He is 33 next month, though, which might count against him for clubs considering a move.

READ MORE: Karl Robinson draws out two 'perfect XIs' as he plots summer recruitment

GREG LEIGH

The Jamaican international was released by Morecambe last month, despite making 47 appearances for club and country in 2021/22.

Leigh looked bright when The Shrimps came to the Kassam Stadium in October and could be a useful option at left back for United.

He bagged two goals and four assists in 36 League One appearances for a struggling team last term, suggesting he could contribute at both ends of the pitch.

Leigh might not be first choice for a promotion-chasing side, but he would be a decent back-up in his position.

READ MORE: Oxford United's 2021/22 season in statistics

AARON PIERRE

The 29-year-old joins Shrewsbury teammate Ebanks-Landell in leaving Montgomery Waters Meadow this summer.

Pierre has faced United several times over the years, most notably for Wycombe Wanderers and Northampton Town, so he knows League One well.

The centre back started just 16 games last season so his release was less surprising than Ebanks-Landell’s, but he is at an age where he still has plenty to offer.

Like a few players in this list Pierre may not suit a U’s side that controls possession, even though his power would make the defence more robust.

He has been known to chip in with a few goals, too, which is something United’s defence missed last season.