Could Sebastian be the perfect name for your baby boy? The baby boy name Sebastian is 9 letters long, and contains 4 vowel(s) and 5 consonant(s). Sebastian is a baby boy name that starts with the letter S and ends in the letter N. The baby boy name Sebastian has a popularity of 98% and is ranked 19 in the list of top 1000 most popular baby boy names. If Sebastian 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 Sebastian!