Mentor Ji
Mentor Ji is the Rangers' strict sensei who helps them in their samurai training and provides the team with information on their enemies. He raised Jayden from a young age and trained him to take arms as the Red Samurai Ranger. Like the rangers, he has a Samuraizer-like phone that he communicates with the others and he can use symbol power to perform various tasks.
Jayden's Father
The previous Red Ranger before Jayden. In his last few moments he able to seal Master Xandred away but the seal had not been perfected so it wasn't permanent. He gave Jayden the Lion Folding Zord.
Kevin's Father
Kevin's father was Kevin's strict swimming coach. He supported his son towards his dream of becoming an Olympic swimmer. However, he was actually training his son to become the Blue Samurai Ranger, and subsequently gave Kevin the Dragon Foldingzord.
Farkus "Bulk" Bulkmeier
In his latest misadventure, Bulk becomes inspired by the newest Ranger team to appear. He is well-meaning, but a bit of a dolt, Bulk has big delusions of grandeur that don't often translate to real life. He becomes determined to shape Spike into a great Samurai. As Bulk has no idea what he's doing, and in the face of danger he often runs in the other direction. Bulk and Spike get 'trained' by Drill Sergeant Emily, fish with Antonio, and clog up a geyser with a giant gumball.
Spike
Spike is the hapless son of Bulk's old friend Skull. He attempts to become a Samurai with Bulk's misguided help. He has inherited his father's clumsy tendencies and his snorting laughter and clumsiness. Though he tries to have courage, he is ill-prepared for the dangers that come with being a Samurai. He also has a crush on the Pink Ranger and then Mia when he meets her. He later returned home with his father.
Matthew & Reece
Mike's friends they loving playing video games. They ask Mike where he has been lately so he tells them about joining a new team and fighting monsters were they think he is talking about a video game until a Nighlok attack and Mike rushes off to face it.
Serena
Serena is Emily's older sister, who was originally meant to be the Yellow Samurai Ranger. When Serena became ill the Ape Foldingzord was given to Emily, along with the powers.
Ryan
Ryan was a young kid who played baseball. Doubletone tried to make him give up on his dreams as part of a deal to bring his father home from his US military duties. With help from Jayden and his symbol power he creates an image of his father to ease his worries.
Daisuke
Daisuke is the elder Guardian of the Tengen Gate where the first Samurai Rangers battled the Nighlok army.
The Fisherman
He appeared in Samurai's episode 'Fish out of Water', He rescued Kevin the Blue Samurai Ranger as he was out for too long attempting to catch the Swordfish Zord. Eventually he aided Kevin in catching the Zord by giving him tips and advice.
Dalia
Before she became known as Dayu, she had been recently married to Deker. When their house burnt down, Deker became severely injured she called upon the 'King of the Nighloks', who turned out to be Serrator. She pleaded for their lives to be saved and he turned them into half-Nighloks, their wedding gifts to each other (a shamisen for her and a sword for him) becoming their primary weapons.
Scott Truman
Scott is the RPM Ranger Red from a dimension where robots have taken over and there is just one city of humanity left. Scott follows Professor Cog alone to the world of the Power Rangers Samurai to stop a plot to use Sanzu water to poison his people. The air might be too pure for Scott, so he remains morphed. Hypno-Bolts are used on Scott to fight against Jayden, Mentor notices this and uses Symbol power on them. Scott helps fight against Professor Cog, Sergeant Tread and General Gut and returns back to his dimension through a special train, not before informing Mike that Emily likes him.
Chad
Chad is a new member of the swim team Kevin was once part of. Chad has never met Kevin but is in awe with his ability and stats and thinks of him as a legend. He once accidentally bumped into Kevin at their pool, and immediately rushed to tell his team, excited for his "return".
Noah
Noah is a member of Kevin's old swimming team. He was mad at Kevin for quiting during the big competition to become a ranger. When he left, he was mad at him after leaving. He replaced Kevin with Chad. Chad told Noah Kevin returned but he said that Kevin isn't one of them anymore. But when he gets a cramp and starts drowning, Kevin rescues him and then he lets Kevin replace him from the cramp. Later, forgives Kevin and becomes friends again.
Cody
Cody is a young boy who is a descendent of were the Samurai's Guardians. Since he was small, he's had the ability to communicate with the BullZord. He leaves his home in order to find the Samurai Rangers which sets him in Serrator's crosshairs. Feeling that his father nor Jayden took him seriously, he decided to enter the BullZord to tame it and eventually does after a few attempts.
Cody's Father
The family guardian of the first Samurai. He was reluctant to release the Bullzord as he feared it was uncontrollable. He was disappointed to see his son defy the Guardian rule that the BullZord be kept hidden, and while he acknowledged that Cody can communicate with the BullZord, he maintained that it cannot be trusted. Despite his earlier misgivings, when Cody was finally able to tame the BullZord, he told Cody how proud he was of him.
The Grand Shogun
He was one of the old Samurai Rangers who entrusted the guardians to guard the untamable Bull Zord. The Bull Zord was to never be freed, but in current times, Cody was able to tame it along with Jayden. Grand Shogun appeared before them and promised him that now the power belonged to him and the new Rangers. The Grand Shogun power was transferred into a new Shogun Disk for the Rangers to use the Shogun Mode. His voice is similar to Zordon's.
Terry
Terry is Mia's brother. Working to get into med school, he is also a guitarist for a rock band. Back when he and Mia were young, they dreamed of being in a band together. Terry invited Mia to sing with him at a concert. However Mia believed it'd be easier for him to get into med school than be a rockstar. Terry left disappointed his sister wouldn't help him, but found a singer in Antonio instead. When Mia found out the concert was actually for charity, she joined her brother and Antonio in the concert.
Skull
Eugene "Skull" Skullovitch is Spike's father and came to pick him up once the Samurai Rangers saved the world from the Nighlok. He came in a limo and thanked Bulk for taking care of his son. He went to high school with Bulk and they are old friends, but it is not clear if Bulk is Spike's uncle because of marriage or anything similar.