One such appears to be St Vladimir the Great, who is revered as a saint by Churches in communion with both Constantinople and Rome. That said, it's not clear when he was canonised — that might have occurred before the Great Schism; and nor is it clear whether this is a local celebration or one recognised by Rome for the whole Church.
According to Wikipedia, St Seraphim of Sarov was called Saint by Pope Bl John Paul II in his book Crossing the Threshold of Hope.
Wikipedia also claims that St Sergei of Radonezh is recognised in the Roman Canon, but there appears to be little or no corroboration for this. In fact, the list of saints is so long that there exists no complete version, so it's probably not easy to confirm or deny it categorically, particularly in view of what is taught about saints...
The Catechism of the Catholic Church, at para 945–962, explains the communion of the saints, and there appears to be no reason why Christians of Churches temporarily in imperfect communion with Rome could not be held as saints. The Catechism quotes Lumen Gentium:
We worship Christ as God's Son; we love the martyrs as the Lord's disciples and imitators, and rightly so because of their matchless devotion towards their king and master. May we also be their companions and fellow disciples!