The name Gwilym signifies descent from the legendary 'Gwilym of doom', a heartless pirate said to have singlehandedly (he had a hook) plunder the entirety of the United Kingdom, only to disappear into mystery. People with the name should be regarded with fear and awe. Also can be used for individuals with such attributes.
"That kid's a Gwilym"
by Spon December 25, 2004