Can ministers of other denominations marry people in a Catholic church? Can ministers from other Christian denominations, for example a United Church Reverend, perform the marriage sacrament in a Catholic Church?
According to the United States Conference of Catholic Bishops,


  It’s popular, and acceptable, for an interfaith couple to invite the non-Catholic spouse’s minister to be present at the wedding. But it’s important to note that, according to canon law, only the priest may officiate at a Catholic wedding. A minister may offer a few words, but he or she may not officiate or preside at a joint ceremony.


While I wouldn't say a non-Catholic marriage in a Catholic church has never happened (and if I did, it would be hard to prove :), but it would be rare at best, akin to holding services for non-Catholic faiths in a Catholic Church.

FYI, for the a Catholic marriage to be considered sacramental, both must be Catholic, and for the marriage to be performed at all requires at least one to be Catholic. (Source)