The boy’s name Cassian \c(a)-ssian\ is pronounced KASH-en. It is of Latin origin. From clan name Cassianus, an elaboration of Cassius. Name of several early saints.
A baby name that sounds like Cassian is Ghassan. Other similar baby names are Caspian, Carsan, Cassidy, Cassiel, Cassio, Hassan and Ossian. (thinkbabynames.com)
New Zealand Baby Names 
Sebastiane said,
July 7, 2009 @ 4:21 pm
Cool name!
Natty said,
July 9, 2009 @ 6:12 pm
My son’s name is Cassian. LOVE the name and so do all who meet him. 🙂
Nita Longatti said,
August 6, 2009 @ 10:32 pm
Hi there –
do you pronounce his name “Kass-ien” or “Kash-en”?
Thank you
babynamelover said,
August 7, 2009 @ 7:53 am
I like it Kass-ien thats how I would say it. but I think the “actual” pronounciation is Kash-en.
babynamelover said,
July 15, 2009 @ 1:48 am
Ooh kewl what is your sons middle (s) names? what a great choice you made 🙂