Special Agent Sam Hanna

Sam Hanna is a main character on the series NCIS: Los Angeles which itself is a spin-off of the original "NCIS" series.

Like his partner, Special Agent G. Callen, Sam is an agent for the Naval Criminal Investigative Service's Office of Special Projects in Los Angeles, California and also a former SEAL associated with the United States Navy.

Pre-Series
Born to an unnamed mother and father in Brooklyn, New York, Sam's dream from a very early age was to be a Navy SEAL.

After finishing high school, Sam presumably enlisted in the Navy and finally achieved his dream of becoming a SEAL. During his time as a SEAL, Sam served in Bosnia, Afghanistan, and Iraq and while on one mission in Bosnia, Sam along with another member of his unit, Dickerson were both captured and tortured before being buried alive.

Dickerson who was shot later succumbed to his wounds and died while Sam was eventually rescued by the other members of their team.

During one of his missions as a SEAL, Sam met Lieutenant Commander Steve McGarrett, presumably working under him, as Steve out ranks him. The two become good friends with Sam commenting that Steve owns him a steak dinner.

Sam eventually left the military with the rank of Senior Chief Petty Officer and applied to join NCIS which resulted in him being assigned to the Office of Special Projects in Los Angeles.

NCIS Season 6
Like the other members of the OSP team, Sam made his debut appearance during the NCIS Season 6/backdoor pilot episode, Legend Part 1 where he was seen assisting fellow agent Kensi Blye tracking down Marine Nick Chandler.

In Legend Part 2 (episode), Sam participated in the gunfight at the auto-shop and was also successful in non-fatally wounding terrorist Haziq Khaleel, enabling OSP to take Haziq into custody.

Sam was also present when Callen was left gravely wounded in a drive-by shooting during Legend Part 2 (episode) and after shooting at the assassins who later fled, arrived on scene, tending to Callen while also calling for an ambulance as Sam urged Callen to stay with him.

In Semper Fidelis (episode), it was revealed that Sam along with Agent Lara Macy had successfully conducted Haziq's interrogation with Haziq telling them the name of his handler: Abin Tabal.

NCIS: Los Angeles Season 3/Hawaii Five-0 Season 2
Upon learning from H50's temporary leader, Detective Danny Williams that a suspect, Dracul Comescu a Romanian criminal and one of Callen's enemies was spotted on Hawaii, Callen and Sam flew to Hawaii to form a partnership with the H50 Task Force and during the introductions, Lieutenant Chin Ho Kelly told Sam that Steve spoke very highly of him, causing Sam to remark, "I'm sorry he's missing the party".

Upon arriving in Hawaii, Callen and Sam formed new friendships with the Hawaii Five-0 team that Danny was temporarily leading due to the fact that the normal team leader, Lieutenant Commander Steve McGarrett was out of the country.

In the field, Sam was temporarily paired with Danny while Callen worked with Chin.

After Comescu died at Callen's hands, the teams had a celebratory dinner at The Shrimp Truck where during the dinner, Sam decided to give Danny's Camero the name "Winnifred" or Winny for short despite Danny insisting that the name sounded like someone's grandmother although Callen and Chin agreed on "Winnifred".

Unfortunately, the dinner ended abruptly after Danny presumably informed them that the vials they had gotten from Comesuc didn't contain any smallpox.

Things took a grave turn when Sam contacted NCIS Tech Operator Eric Beale and told him that OSP's Manager, Henrietta Lange needed to send a team to LAX straightway, only to hang up and inform the others that the flight had arrived in LA five minutes ago.

As a result, Sam and Callen returned to LA with Danny and Chin coming along to help given how intense the situation had gotten.