Vicente del Bosque's side have beaten all comers over the past few years and were as impressive as ever in qualification, winning every single one of their matches on the road to Poland and Ukraine.
They will meet Italy, their predecessors as World Cup winners and a side undergoing a rebuilding process under coach Cesare Prandelli. The Azzurri have had plenty of injury worries up front but are never to be counted out, having seen off Serbia and Slovenia in their qualifying group.
Ireland are perhaps the tournament's biggest underdogs but, backed by passionate fans, they fought their way past Estonia in the play-offs and will feel that they have nothing to lose in a group with such illustrious opponents.
Croatia round out the group, having finished behind Greece on their way to the tournament, but they will be hardly there just to make up the numbers.
With the tournament proper only a month away, Goal.com has looked back in detail at the qualification stories of each side to see what we can possibly expect in Group C this summer.
Spain have been the best international team in world football for the past four years. Having won two major tournaments in Euro 2008 and World Cup 2010, everyone considered Vicente del Bosque's men as the team to beat when the qualifying for Euro 2012 commenced.
The holders were clear favorites in a group consisting of closest challengers Czech Republic, Liechtenstein, Lithuania and Scotland, and in the end breezed through Group I with little trouble along the way.
Their first two matches were simple wins over the minnows of the group, Liechtenstein and Lithuania by 4-0 and 3-1 scores respectively. Fernando Torres collected his only two goals on the road to Euro 2012, but Spain's most difficult test in the group came at Hampden Park against Scotland. Leading 2-0 through Barcelona duo David Villa and Andres Iniesta, they allowed the hosts to pull back to 2-2. However, a late volley from Fernando Llorente sealed a 3-2 win in dramatic circumstances.
La Furia Roja’s dominance continued from that point on. A Villa double saw off Czech Republic, who eventually finished second in Group I and entered the play-offs. Two more convincing wins over Lithuania (3-1) and Liechtenstein (6-0) took all the pressure off before their final two fixtures.
Playmaker David Silva inspired the visitors in Prague as Juan Mata and Xabi Alonso strikes earned a comprehensive 2-0 victory before they ended Scotland’s dreams of even making the play-off in their final qualifier with a 3-1 success at the Estadio Jose Rico Perez - Silva and Villa on target once more.
Del Bosque’s side ended qualifying with a perfect record of eight wins and no draws or losses, and a goal difference of +20. They waltz their way into Poland and Ukraine as favourites, and will be confident of retaining the title they won four years ago in Austria and Switzerland.
After a disastrous World Cup 2010 that saw them crash out of a fairly modest group in South Africa, Italy appointed a new coach in Cesare Prandelli as they looked to rebuild and reach Euro 2012.
Despite their struggles in Africa, the 1968 winners were still viewed as the cream of the crop in a Euros qualifying group containing Estonia, Faroe Islands and Northern Ireland, although Serbia and Slovenia were expected to provide some stern competition.
Their first match was not without a scare as Estonia took the lead in Tallinn but Antonio Cassano, recalled after being left in the cold by Prandelli's predecessor Marcello Lippi, scored a goal and assisted the winner as the Azzurri began their campaign on the right foot.
The following fixture was far more straightforward, as many praised Prandelli’s more fluid style of football as his team thumped the Faroe Islands 5-0 in Florence with a textbook Andrea Pirlo set-piece rounding off the emphatic scoreline.
In October 2010, a stubborn Northern Ireland team held Prandelli’s side to a 0-0 draw in Belfast, and the dull affair quelled the enthusiasm. However, four days later came the Azzurri’s most important win of the qualifiers - a match that led to Serbia’s failure to reach the finals.
The Marassi was the stage for the all-important clash with the eastern Europeans, but crowd trouble and riots from the visiting fans eventually caused the match to be suspended. Italy were later awarded a 3-0 win by Uefa and, while it soothed the hosts’ path, the Serbians never truly recovered as they also had to play their next two home matches behind closed doors.
Another boost arrived when Brazilian-born Thiago Motta struck the lone goal in a crucial away victory over rivals Slovenia, and routine victories over Estonia and Faroe Islands then followed.
Inter striker Giampaolo Pazzini secured the Azzurri’s place at the competition with two matches to spare as he came off the bench to slam home the winner in a narrow 1-0 triumph over Slovenia. Italy rounded off Group C with a 1-1 draw in Serbia - which saw Claudio Marchisio break his duck for the national team - and a 3-0 win over Northern Ireland in which Cassano struck twice to end qualifying as his team’s top scorer with six goals. Overall, Italy finished their section with a relatively impressive record - unbeaten after 10 matches with eight wins and two draws - a full 10 points ahead of second-placed Estonia.
Some concerns surround Italy’s attacking options at Euro 2012 going into the tournament. Nonetheless, despite a major health scare for Cassano that required heart surgery to rectify, he appears to be ready to feature to lead the Azzurri’s attack, but strike-partner Giuseppe Rossi has been ruled out of the tournament after injuring his anterior cruciate ligament.
Ireland missed out on World Cup 2010 in the most controversial of circumstances following Thierry Henry’s infamous handball, but this time their hard work paid off as they reached Euro 2012.
In Group B, many expected Russia and Slovakia to fight it out for a place at Poland and Ukraine with Giovanni Trapattoni’s men, as Andorra, Armenia and Macedonia rounded off the list of opponents.
Keith Fahey’s winner in Armenia started the Irish campaign off with a 1-0 victory in September 2010 just days before Robbie Keane struck the final goal in a 3-1 win over hapless Andorra, who lost all 10 of their matches.
Unfortunately for the Boys in Green they were no match for Russia, who raced into a 3-0 lead in Dublin and held out for a 3-2 win despite a late comeback.
Defender Sean St Ledger’s early goal in Slovakia allowed the visitors to earn a 1-1 draw in October, but Keane missed the chance to hand his side all three points by missing a crucial penalty that could have changed the complexion of the group.
Consecutive wins home and away against Macedonia, in which LA Galaxy striker Keane scored three of his side’s four goals, put Trapattoni’s men back on track, but a disappointing scoreless draw against Slovakia was followed by a fortunate 0-0 draw in Moscow versus Russia.
Kevin Doyle and Spartak Moscow playmaker Aiden McGeady propelled the Irish to a 2-0 win over Andorra to end the goal-drought with one match left.
Nonetheless, it was not until their final Group B fixture that Ireland clinched a place in the playoffs, ending the dreams of an Armenia side that had performed above expectations. Both countries finished the game with 10 men, but it was Richard Dunne’s tap in that resulted in a 2-1 victory and allowed his side to finish second in their section on 21 points from 10 matches, two points behind Russia.
Facing shock Group C runners-up Estonia in the playoff for a place at the European Championship, Ireland all but booked their place in the first leg, winning 4-0 in Tallinn on the back of Keane’s brace, before a 1-1 draw in the second leg.
Slaven Bilic’s Croatia have never been shy about announcing their intention to improve on their quarter-final shootout loss to Turkey in 2008. But their first task was to qualify for Euro 2012 by emerging from a section consisting of Georgia, Israel, Latvia, Malta and 2004 winners Greece.
A rosy start saw them dispose of Latvia on the road, with captain Darijo Srna’s goal rounding off a straightforward 3-0 triumph while a scoreless draw against Greece in their second fixture was also a positive sign.
Niko Kranjcar’s double in Tel Aviv overcame challengers Israel and the Tottenham midfielder was once again the hero with another two goals as a 3-0 victory over Malta allowed them to jump to the top of Group F.
However, in March 2011, a 1-0 defeat at Georgia proved to be a surprise setback, but Bilic’s side would recover to win their next three qualifiers, first repaying the favour to Georgia with a 2-1 win in Split that featured late goals from Mario Mandzukic and Nikola Kalinic, followed by a 3-1 triumph against lowly Malta, who eventually finished with just a single point from 10 games. It was then ex-Arsenal striker Eduardo’s turn to be the star as he scored twice in another crucial victory over Israel (3-1).
Croatia’s bid to finish top of Group F took its heaviest hit when they suffered a 2-0 loss away to Greece in their penultimate match, succumbing to second-half strikes from Giorgios Samaras and Theofanis Gekas. A 2-0 win in their final fixture was not enough to overcome the Greeks in terms of topping the table, as Bilic’s side finished two points behind the Ethniki in the final standings.
The play-offs beckoned, and the Croatians were very much up to the task as they demolished Guus Hiddink’s Turkey 3-0 away from home in the first leg thanks to goals from Ivica Olic, Mandzukic and Vedran Corluka. The second leg lacked the same lustre as the first, as the teams played out a 0-0 stalemate.