#1 Philippe Coutinho - €135 million

Barcelona signed Philippe Coutinho from Liverpool for €135 million in the January transfer window of 2018, which makes him the most expensive Barcelona player of all time.
The Brazillian international started his professional career with Inter Milan and joined Liverpool in 2013. He established himself among the best players in the Premier League with the Reds and won the Liverpool Players' Player of the Season accolade twice.
However, the Merseysiders' failure to win any major trophy made it difficult for them to keep hold of their superstar. He eventually made the switch in 2018 after submitting the formal transfer request to the club.
It began well enough for the Brazillian at the Camp Nou and he scored 10 goals in 22 appearances during his first half season with the club. However, he has suffered from injuries and bad form this season, and is currently struggling for game time at the club.
Coutinho has been linked with a shock exit during the January transfer window, and Barcelona's latest recruitment of Frank de Jong creates more doubts over his long term future at the club.