Greg K is well-known for his tranquility, his dicration and the back-and-forth movement he does with his pelvis when he plays on stage. Born on 1965 in California, he is one of the founding members of the band alongside singer Dexter Holland. Manic Subsidal and later, The Offspring, played their first gigs in Greg K's house, in the middle of the living room.

He was on the track and field team in Pacifica High School from Garden Grove along with his fellow bandmate. Dexter and him met there for the first time. Gregory was also in the Math Club. Later, he attended Golden West Junior College and recieved a B.A. in finance from Long Beach State while working part time in a print shop. He was planning to attend law school and never attend because of his band.

Greg's hobbies include golf, base jumping, fishing, camping and he also collects hats. He is married to a girl named Jane and has four sons. He currently lives with them in Cypress, California.