Backs
Stuart Hogg (Scotland)
Position: Fullback
Age: 28
Club: Exeter
Caps: 85
Lions Tests: 0
Form guide: Scotland captain will challenge strongly to make the Lions Test team.
Liam Williams (Wales)
Position: Fullback/wing
Age: 30
Region: Scarlets
Caps: 71
Lions Tests: 3
Form guide: Huge success on the Lions' 2017 New Zealand tour, and his form has not waned.
Anthony Watson (England)
Position: Fullback/wing
Age: 27
Club: Bath
Caps: 51
Lions Tests: 3
Form guide: Outstanding and consistent form makes a Test team place highly likely.
Josh Adams (Wales)
Position: Wing
Age: 26
Region: Cardiff Blues
Caps: 32
Lions Tests: 0
Form guide: Top try-scorer at the 2019 World Cup, his finishing ability is unquestioned.
Louis Rees-Zammit (Wales)
Position: Wing
Age: 20
Club: Gloucester
Caps: 9
Lions Tests: 0
Form guide: Burst on to the Test scene this season and made a blistering try-scoring impact.
Duhan Van Der Merwe (Scotland)
Position: Wing
Age: 25
Club: Edinburgh
Caps: 10
Lions Tests: 0
Form guide: Eight tries in 10 Tests underlines the finishing ability of the South Africa-born wing, who qualifies for Scotland on residency.
Bundee Aki (Ireland)
Position: Centre
Age: 31
Province: Connacht
Caps: 31
Lions Tests: 0
Form guide: A real left-field selection by Lions boss Gatland, but the Ireland centre is an experienced campaigner.
Elliot Daly (England)
Position: Centre
Age: 28
Club: Saracens
Caps: 52
Lions Tests: 3
Form guide: Another surprising selection, given his poor form in the recent Six Nations, but he has Lions experience.
Chris Harris (Scotland)
Position: Centre
Age: 30
Club: Gloucester
Caps: 28
Lions Tests: 0
Form guide: Outstanding for Scotland in the Six Nations this season, and deserves his Lions chance.
Robbie Henshaw (Ireland)
Position: Centre
Age: 27
Province: Leinster
Caps: 52
Lions Tests: 0
Form guide: The form centre in this season's Six Nations is on course for a Lions Test spot.
Owen Farrell (England)
Position: Outhalf/centre
Age: 29
Club: Saracens
Caps: 93
Lions Tests: 4
Form guide: Proven Lions pedigree in 2017, but struggled for form during this season's Six Nations.
Dan Biggar (Wales)
Position: Outhalf
Age: 31
Club: Northampton
Caps: 92
Lions Tests: 0
Form guide: Favourite for the Lions Test outhalf role after starring for Wales in their Six Nations title-winning campaign.
Finn Russell (Scotland)
Position: Outhalf
Age: 28
Club: Racing 92
Caps: 55
Lions Tests: 0
Form guide: Playmaker who shone for Scotland in the Six Nations. Magical on his day.
Conor Murray (Ireland)
Position: Scrumhalf
Age: 32
Province: Munster
Caps: 89
Lions Tests: 5
Form guide: Hugely-experienced player who was key for the Lions in New Zealand four years ago. Test place likely.
Ali Price (Scotland)
Position: Scrumhalf
Age: 27
Club: Glasgow
Caps: 42
Lions Tests: 0
Form guide: Has landed one of the Lions scrumhalf roles following a solid season with Scotland.
Gareth Davies (Wales)
Position: Scrumhalf
Age: 30
Region: Scarlets
Caps: 62
Lions Tests: 0
Form guide: Possesses searing pace and an eye for tries, he can change games in an instant.
Forwards
Wyn Jones (Wales)
Position: Prop
Age: 29
Region: Scarlets
Caps: 35
Lions Tests: 0
Form guide: Impressive during Wales' Six Nations title campaign this year. Strong Test team claims.
Mako Vunipola (England)
Position: Prop
Age: 30
Club: Saracens
Caps: 67
Lions Tests: 6
Form guide: Had his share of injuries, but offers an enormous amount of quality and experience.
Rory Sutherland (Scotland)
Position: Prop
Age: 28
Caps: 16
Lions Tests: 0
Form guide: Impressed for Scotland this season through admirable consistency.
Deserves his Lions chance.
Zander Fagerson (Scotland)
Position: Prop
Age: 25
Club: Glasgow
Caps: 38
Lions Tests: 0
Form guide: Solid performer for Scotland this season, who is part of a strong Lions frontrow contingent.
Tadhg Furlong (Ireland)
Position: Prop
Age: 28
Province: Leinster
Caps: 49
Lions Tests: 3
Form guide: Currently shades the contest for a Test team place.
Andrew Porter (Ireland)
Position: Prop
Age: 25
Province: Leinster
Caps: 37
Lions Tests: 0
Form guide: Behind Furlong in the pecking order for Ireland and Leinster, but a player who consistently impresses.
Ken Owens (Wales)
Position: Hooker
Age: 34
Region: Scarlets
Caps: 82
Lions Tests: 2
Form guide: Returned from injury to shine in this season's Six Nations. An experienced leader.
Jamie George (England)
Position: Hooker
Age: 30
Club: Saracens
Caps: 59
Lions Tests: 3
Form guide: Key Lions Test team performer in 2017, and will have a thirst for more action in South Africa.
Luke Cowan-Dickie (England)
Position: Hooker
Age: 27
Club: Exeter
Caps: 31
Lions Tests: 0
Form guide: A destructive forward who is a handful for any opponent. Will relish his Lions chance.
Maro Itoje (England)
Position: Secondrow
Age: 26
Club: Saracens
Caps: 48
Lions Tests: 3
Form guide: Likely to be among the first names on Gatland's Test team-sheet. World-class.
Jonny Hill (England)
Position: Secondrow
Age: 26
Club: Exeter
Caps: 9
Lions Tests: 0
Form guide: Continues his rapid emergence on the international scene with his Lions selection. All-action performer.
Courtney Lawes (England)
Position: Secondrow
Age: 32
Club: Northampton
Caps: 87
Lions Tests: 2
Form guide: Currently sidelined through injury, but should be back in action soon. Could make a major Lions contribution.
Alun Wyn Jones (Wales, captain)
Position: Secondrow
Age: 35
Region: Ospreys
Caps: 148
Lions Tests: 9
Form guide: Gatland's choice as captain is the squad's most experienced player. Fourth Lions tour, and remains in peak form.
Iain Henderson (Ireland)
Position: Secondrow
Age: 29
Province: Ulster
Caps: 63
Lions Tests: 0
Form guide: Will be an important part of the squad. Vastly-experienced and a possible midweek team captain.
Tadhg Beirne (Ireland)
Position: Secondrow/backrow
Age: 29
Province: Munster
Caps: 22
Lions Tests: 0
Form guide: Consistency personified for Munster and Ireland. Will be in Test team shake-up.
Jack Conan (Ireland)
Position: Number eight
Age: 28
Province: Leinster
Caps: 28
Lions Tests: 0
Form guide: Outstanding in Leinster colours over an extended period. Strong performer.
Tom Curry (England)
Position: Flanker
Age: 22
Club: Sale Sharks
Caps: 33
Lions Tests: 0
Form guide: One of the world's finest players on current form. Appears a Test team certainty.
Justin Tipuric (Wales)
Position: Flanker
Age: 31
Region: Ospreys
Caps: 85
Lions Tests: 1
Form guide: One of the most naturally-gifted forwards in world rugby. Strong in all departments.
Hamish Watson (Scotland)
Position: Flanker
Age: 29
Club: Edinburgh
Caps: 41
Lions Tests: 0
Form guide: This season's Six Nations player of the tournament who is rightly among Gatland's backrow riches.
Sam Simmonds (England)
Position: Number eight/flanker
Age: 26
Club: Exeter
Caps: 7
Lions Tests: 0
Form guide: Overlooked by England boss Eddie Jones since 2018, but is arguably the Premiership's most consistent player.
Taulupe Faletau (Wales)
Position: Number eight/flanker
Age: 30
Club: Bath
Caps: 86
Lions Tests: 4
Form guide: Test team certainty. Back to his very best, which will be a concern for the Springboks.