There are several Alyns:

Alyn : a member of the household guard of Lord Eddard Stark at Winterfell. He dreams about becoming a knight.

Alyn of the Rosewood : a member of the nightwatch

Alyn Ambrose : Son of Lord Arthur Ambrose

Alyn Connington : former Lord commander of Kingsguard

Alyn Estermont : so of Aemon Eastermont

Alyn Frey : member of House Frey

Alyn Haigh : a squire

Alyn Hunt : A knight of House Hunt

Alyn Stackspear : a Knight of House Stackspear

Alyn Velaryon : A former Admiral of Westeros