Captain William Mitchell (Sigma Series)

Captain William "Bill" Mitchell is the head of the Lightspeed Aquabase, mentor of the Lightspeed Rescue Power Rangers and the father of Dana, Jane, and Ryan Mitchell.

Background
Captain Mitchell was responsible for selecting the Lightspeed team, each Ranger was chosen for their special skills and abilities in a specific area. Throughout the season, Mitchell uses his wisdom to provide the Rangers crucial information regarding their enemies or missions. A firm believer in following the rules, Mitchell often comes off as aloof or unfeeling toward the Rangers. His tendency to withhold information from them, typically in an attempt to allow them to realize a mistake made on their part or security reasons, he's been accused for making bad judgement calls.

When he gives the order for Carter to put out a fire instead of saving civilians and his daughter in peril, the order results in the injury of a young boy and Jane. Believing he could've prevented the injury, Carter argues Mitchell made a bad call until he realizes why Mitchell had ordered the fire be put out first; a tank of flammable liquid had been present. Had Carter not done as ordered, everyone (including himself) would've perished in an explosion. On another occasion, his daughters, Dana and Jane, thought he did not value they like the other Rangers when they was sent to escort an old friend of his to the docks to fish. Once it's revealed that his friend was actually in possession of the nuclear device the other Rangers were believed to be protecting, Dana and Jane realizes that their father trusted them more than previously they believed.

Years before the events of the season, Captain Mitchell lost his son, Ryan, to the demon, Diabolico after a car crash. Hanging from the root of a tree on the face of a cliff, Mitchell was put in situation in which he could only save Dana and Jane. Diabolico promised to save his son, but in return, he asked for ownership over Ryan. Mitchell agreed to the terms and was told he would not see his son again until hist twentieth birthday. Over the years, Diabolico managed to make Ryan believe that his father abandoned him to the demons in favor of his daughter. After a torrid series of battles against a now 20 Ryan as the Titanium Ranger, Mitchell successfully convinced Ryan to leave Diabolico's side and join him as the Lightspeed team.

Triva

 * Mitchell is the first known Power Rangers Mentor to be a parent of a Ranger.
 * It should also be noted that Captain Mitchell is the first human mentor of the Power Rangers franchise