Steven McGarrett

Steve McGarrett's Grandfather died on the USS Arizona during the attack on Pearl Harbor by the IJNA on December 7th, 1941. His Grandson was named after him.

In Season 4 Episode 10 -Ho'onani Makuakane (Honor Thy Father)- we learn that he would attend tutoring sessions with James Toriyama to prepare for an officer aptitude test. He was last seen by Mr Toriyama's youngest son, David Toriyama, on December 6, 1941when he presented him with a gift for his father's help.

During season 7 episode 22 - Waimaka 'ele'ele - Steve learns that his grandfather went back down into the USS Arizona to flood the ammo shed so that the flames would not reach it during the bombing of Pearl Harbor. This allowed other sailors on the ship to make it off. Steve is unsure if anyone knew about this. Ensign McGarrett was awarded the purple heart posthumously.

In Season 9, episode Pua a'e la ka uwahi o ka moe we meet Steven's grandfathers best friend Milton Cooper (retired HPD detective) and learn that his grandfather wanted to become a police detective. Milton gives Steve his grandfather attache case which has a old case file in it and repeatedly notes how much Steve looks like his grandfather.