Who would make El Clasico's all-time Best XI?

El Clasico is a rivalry that really needs no introduction. Barcelona and Real Madrid, two of today’s biggest, most successful and richest clubs in not just soccer but all of sports, have engaged in their bitter, strongly politicized feud since the 1930s.

Through the years, the rivalry has provided the world with scores of unforgettable moments and, more importantly, some of the finest footballers the world has ever seen.

So, who would make a hypothetical all-time El Clasico Best XI? With so many legendary players on both sides it was almost an impossible task, and there were always going to be some glaring ommissions, but we gave it a shot anyway. (Disclaimer: This isn't strictly a 'Best Players' list. We tried to build a functional team).

Iker Casillas, GK, Real Madrid

One edge Real has mostly enjoyed over Barcelona for the last couple decades has been between the posts, and Casillas was the biggest reason for it. "Saint Iker" is arguably the greatest goalkeeper in Real's storied history, making 725 appearances in 16 seasons at the Bernabeu and winning 18 trophies, including three Champions League titles.

Roberto Carlos, LB, Real Madrid

The Brazilian legend became a fan favorite for his marauding 90-yard runs and powerful free kicks. Roberto Carlos was part of the original "Galacticos" alongside Zidane, and has 512 appearances and 67 goals to his credit in ten seasons. His goal against Barcelona in 2002/03 also counts among the rivalry's best ever.

Fernando Hierro, CB, Real Madrid

Club legend Raul has dubbed Hierro the "captain of all captains," and his record certainly backs it up. One of the best attacking central defenders of all-time with 134 goals to his credit, Hierro led Real to three Champions League trophies and five La Liga titles between 1989 and 2003.

Ronald Koeman, CB, Barcelona

A member of Barca's famous "Dream Team" under Johan Cruyff, Koeman spent time in central midfield and defense during his six years with the club. The deep-lying Dutch playmaker won four league titles and scored the game-winning goal in extra time of the 1991/92 European Cup final. Oh, he also scored five times against Real Madrid in those six seasons.

Carles Puyol, RB, Barcelona

What Hierro had meant to Real, Puyol meant to Barca. The shaggy-haired and rugged defender plays out wide in this Best XI, as he did at the start of his career at the Camp Nou. Under Puyol's captainship, Los Cules entered their current golden era and he amassed 593 appearances and 21 trophies for the only club he's ever known.

Xavi, CM, Barcelona

This season has been the first in the millennium in which Xavi has not featured in El Clasico. The all-time record holder with 42 Clasico appearances (along with Real's Francisco Gento and Manuel Sanchis), the tiki-taka master has inspired a generation of possession-oriented playmakers in the middle of the field since his arrival at the Camp Nou.

Alfredo Di Stefano, CM, Real Madrid

Many of the elder Real faithful still call Di Stefano the greatest player in the club's history. In eleven seasons, Di Sefano scored 307 goals and won five European Cups, eight La Liga titles and two Ballon d'Ors. Capable of playing in attack, midfield, and defense, Di Stefano did whatever his team asked, so we will place him alongside Xavi to back up the brilliant attackers ahead of him.

Zinedine Zidane, CAM, Real Madrid

The greatest player of his generation is firmly entrenched in the No. 10 role for our all-star squad. Zidane scored 45 goals and won six trophies in five seasons with Real, and played a pivotal role in the 2001/02 Champions League triumph, scoring the unforgettable winner in the final against Bayer Leverkusen, and adding another goal in the semifinals against, yes, Barcelona. 

Johan Cruyff, RAM, Barcelona

The late Dutch legend, who'll be honored at the Camp Nou on Saturday, led Barcelona to their first La Liga title since 1960 in his very first season in 1973/74, scoring in the famous 5-0 win at the Bernabeau along the way. A Copa del Rey is all he would add to his haul as a Barca player, but the impact he would later have on the team -- and the sport -- as manager was far more important. 

Cristiano Ronaldo, LAM, Real Madrid

This season, Ronaldo became both his club's and the Champions League's all-time leading scorer, and trails only Lionel Messi with 253 La Liga goals...in just 230 games. Fifteen career goals in El Clasico put him solely behind Messi and Di Stefano on the all-time list, while CR7 also holds the record for scoring in six consecutive Clasicos between 2011 and 2013.

Lionel Messi, FWD, Barcelona

He's won a record five Ballon d'Ors, four Champions League trophies, is Barca's all-time leading scorer and amassed countless of other records, and he's still only 28. Messi is also El Clasico's all-time top scorer with 21 goals in 28 games, including two hat tricks. Quite simply, he's the best player in the history of this matchup, and when it's all said and done, he may be the best player ever. Period.