Could Onyx be the perfect name for your baby boy? The baby boy name Onyx is 4 letters long, and contains 1 vowel(s) and 3 consonant(s). Onyx is a baby boy name that starts with the letter O and ends in the letter X. The baby boy name Onyx has a popularity of 26% and is ranked 745 in the list of top 1000 most popular baby boy names. If Onyx isn't the ideal name for your baby boy then take a look here for some randomly generated names. Hopefully you'll find a more suitable first name for your baby boy than Onyx!