CTT – Correios de Portugal, S.A. (lit. 'CTT – Post of Portugal') is a Portuguese company that operates as both the national postal service of Portugal and a commercial group with subsidiaries operating in banking, e-commerce, and other postal services. It was founded in 1520 by King Manuel I of Portugal, during the Portuguese Renaissance, and CTT is the oldest company still in operation in Portugal to this day.

The acronym CTT comes from the company’s former name (Portuguese: Correios, Telégrafos e Telefones, which means "Post, Telegraph and Telephone"), which was also the designation of postal services for the former Portuguese Colonies and is still used for CTT – Post of Macau today.

In 1991, CTT became a public limited company, and in December 2013 its shares were listed on Euronext Lisbon.

In 2007, CTT began to offer a mobile phone service in Portugal, under the brand name Phone-ix. Phone-ix was closed down on 1 January 2019.

In 2014, CTT was privatized by the Portuguese government to raise money and comply with European Union requirements for its bailout. In the previous year, 70% of the CTT shares had already been tendered.

Its current and longest-running visual identity (that were introduced on 4 October 2004) were receiving subsequent redesigns in July 2015 and March 2020, but its logo (the current one that were introduced on 4 October 2004) remains virtually unchanged.