Cathy Maguire, also spelt Kathy, is played by Northern Irish actress, Bronagh Waugh, who is 37-years-old.
She is known for her role as Cheryl Brady in Hollyoaks, and she has been nominated for a number of soap awards.
The star was nominated for two National Television Awards, in 2010 for her role as Cheryl in the Channel 4 soap.
She only appeared in one episode of Derry Girls, but she became one of the most talked-about characters.
Her other TV credits include Unforgotten, The Fall, Supernatural and Fiddler Walk.