Wikipedia says:
In the Catholic Church, the Pope is regarded as the successor of Saint Peter, the Apostle.
cf. http://en.wikipedia.org/wiki/Pope | Wikipedia
As someone who isn't Catholic I don't want to argue how true this is or how significant this is.
What I'm interested to know is there an office/title/person in the Catholic church for any of the other 11 Apostles (12 if you include Paul), or is it just Saint Peter because he was the leader of the apostles?