Most non polar amino acid is:
Polar and non polar amino acids:
Polarity : Amino acids are classified into 4 groups based on their polarity. The polarity in turn reflects the functional role of amino acids in protein structure. 

Non-polar amino acids: These amino acids are also referred to as hydrophobic (water hating). They have no charge on the 'R' group. The amino acids included in this group are - alanine, leucine, isoleucine, valine, methionine, phenyl-alanine, tryptophan and proline. 
Polar amino acids with no charge on 'R' group: These amino acids, as such, carry no charge on the 'R' group. They however possess groups such as hydroxyl, sulfhydryl and amide and participate in hydrogen bonding of protein structure. The simple amino acid glycine (where R = H) is also considered in this category. The amino acids in this group are - glycine, serine, threonine, cysteine, glutamine, asparagine and tyrosine. 
Polar amino acids with positive 'R' group: The three amino acids lysine, arginine and histidine are included in this group. 
Polar amino acids with negative 'R' group: The dicarboxylic monoamino acids- aspartic acid and glutamic acid are considered in this group.
Leucine
Glycine
Arginine
Lysine