Essential amino acids are named so:

Essential amino acids are so called not because they are more impoant to life than the others, but because the body does not synthesize them, making it essential to include them in one's diet in order to obtain them. They are Leucine, Arginine, Histidine, Isoleucine, Meyhionine, Phenylalanine, Threonine, Tryptophan, Valine and lysine. Additionally, cysteine (or sulphur-containing amino acids), tyrosine (or aromatic amino acids), histidine and arginine are required by infants and growing children.