In the geologic timescale, the Telychian is the third and final age of the Llandovery Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon.

[8] The name of the interval is derived from the Pen-lan-Telych Farm near Llandovery, Powys, Wales.

It occurred at the Llandovery/Wenlock boundary (mid Silurian, 432.9 ± 1.2  million years ago).

The event is best recorded at Ireviken, Gotland, where over 50% of trilobite species became extinct; 80% of the global conodont species also become extinct in this interval.

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