Valtiel is awesome. Closers and Siam are my favourite monsters - though I was disappointed to find out Closer was pronounced like you would pronounce "to close a lid" as opposed to "to come closer."
Indeed!
and really? ... I've been pronouncing it awesomely this whole time, awesomely incorrect ,_,;
Yes, the art books and Ultimania-esque books say that they're called that because they are so large and close doorways and gaps and escape routes with their huge form.