Angus Og

In Poul Anderson's The Broken Sword, when the Tuatha De Danaan from Tir-nan-Og meet in the Cave of Cruachan, the warrior Angus Og sits at the right hand of the king, Lugh of the Long Hand.

Ray Bradbury's title, "The Golden Apples of the Sun," is taken from the poem, "The Song of Wandering Aengus" by WB Yeats. See here. Aengus is Angus.

Two of the Others enter in the forms of Aengus mac Og and Brigit.
-copied from here. 

Thus, Angus/Aengus links:

a fantasy novel by Poul Anderson;
a poem by WB Yeats;
a soft sf short story by Ray Bradbury;
a hard sf novel by Poul Anderson.

And I am not sure whether anyone has noticed this before. I hadn't.