Gardiki Castle, 13th-century Byzantine castle in southwestern Corfu, Greece.

Gardiki is a 13th-century castle with an octagonal layout and eight rectangular towers rising from a hilltop in southwestern Corfu. The site preserves fragments of frescoed walls in its towers and displays the defensive architectural design typical of Byzantine military strongholds.

Gardiki Castle dates from the 13th century and was built by a ruler of the Despotate of Epirus, either Michael I Komnenos Doukas or his son Michael II. It was one of three castles defending Corfu before the Venetian era (1401–1797), forming a defensive triangle with Kassiopi Castle in the northeast and Angelokastro in the northwest. The Corfiote historian Andrea Marmora mentioned it in his 1672 book Della Historia di Corfù.

Andrea Marmora, Corfu's earliest medieval historian, wrote in his 1672 Della Historia di Corfù that the despots of Epirus adorned Corfu with noble buildings and built defences including Gardiki and Angelokastro. The castle's name is not explained in the sources; no garden etymology is recorded. Visitors today see the ruined interior and the eight tiled towers.

The site is best reached on foot from Agios Matheos village by following marked paths that lead to the hilltop. Visitors should prepare for uneven terrain and uphill walking, so sturdy footwear and allowing time for the climb are recommended.

At the rock shelter of Grava Gardikiou on the castle site, Upper Palaeolithic finds dated to around 20,000 BC were recovered, including hunter-gatherer stone tools and animal bones from when Corfu was still joined to Epirus. The finds have been removed and are shown at the Archaeological Museum of Corfu.