The Turkish invasion and the events that followed had drawn the world’s attention to our region at the time, prompting the then Austrian UN Secretary-General Kurt Waldheim traveling to Cyprus in an effort to bring the two sides closer to resolving the issue before it became entrenched.
  He arrived
in Nicosia on January 27, 1977, following numerous consultations in which he actively participated, and held a meeting with Makarios and Denktash.
 
In fact, two weeks later, he had returned to Cyprus to attend a second meeting with the two leaders on February 12, before the two sides were to travel to Vienna for talks.
 
“How is the atmosphere, Mr. Waldheim? The atmosphere is good; there is a willingness to find the means and ways to overcome the difficulties.” ^{Kurt Waldheim, UN Secretary-General (1972–1981)}

And since he failed to achieve his goal—not even two years later during the talks between Spyros Kyprianou and Rauf Denktash— he finally handed over the Secretariat to Pérez de Cuéllar in 1981, to no avail.
 
Kofi Annan
: “We will try to do everything we can to reach a consensus to conclude the talks—at the very least, to reach an agreement on the key issues by the end of the year.” ^{Kofi Annan, UN Secretary-General (1997–2006)}

Freshest in our minds, of course, is Kofi Annan’s visit, when, as part of his efforts to finalize the Plan for a Solution to the Cyprus Problem, he visited Cyprus on May 15, 2002
. Hopes were high at that time, as the then UN Secretary-General met with Glafkos Clerides and Rauf Denktash, a few months before the presidential elections in Cyprus and two years before the referendum.
 
Ban Ki-moon
The most recent visit by a UN Secretary-General to Cyprus took place in February 2010, when the then head of the United Nations, Ban Ki-moon, arrived in Cyprus for a series of meetings as part of efforts to resolve the Cyprus issue.
 
During his visit, he held separate meetings with Dimitris Christofias and Mehmet Ali Talat, as well as a joint meeting aimed at encouraging the continuation of talks under the auspices of the United Nations.
 
“This partnership will result in a federal government with an international character, and the Turkish Cypriot constituent state and the Greek Cypriot constituent state will be equal.” ^{Ban Ki-moon, UN Secretary-General (2007–2016)}

An effort that, once again, proved fruitless.

See the report by Giorgos Chrysanthos