Silver Sentry is a Superman-like superhero based in New York City, and a special friend and occasional partner of Michelangelo.
History[]

Silver Sentry (Season 1-5 style)
Silver Sentry first appears in "The Unconvincing Turtle Titan". While on a training run, the Turtles witness Silver Sentry help the fire department with a burning building and rescue a child that was trapped inside. He serves as the inspiration behind Michelangelo wanting to adopt the superhero way and become Turtle Titan. The Sentry appears later as he saves the Michelangelo from a runaway bus that he stuck to. He warns Michelangelo that being a superhero is a dangerous job. After finding out about the bug robots controlling people, he flies off to defeat his archenemy Doctor Malignus, leaving Mikey behind.
However, Silver Sentry finds himself under the control of Malignus and starts to attack Mikey, who had followed him anyway. Eventually, Mikey is able to destroy the bug and the two team-up to defeat Doctor Malignus. The Sentry thanks the Turtle Titan for his help, resulting in a friendship between the two, and later on a TV interview, Silver Sentry states that he couldn't have defeated Doctor Malignus without the help of Turtle Titan, much to the surprise of Leonardo, Donatello, and Raphael.
Silver Sentry would later join the Justice Force as its leader. He also appeared in "Space Invaders, Part 2", and "The Christmas Aliens"; in the latter episode, it's revealed that he has a passion for chocolate chip cookies.
Lost Episodes[]
Silver Sentry appears in "Membership Drive", and the double episode "Enter the Dragons, Part 1" and "Part 2", where he and the other Justice Force members help the Turtles fight the Tengu Shredder. In the aftermath of the battle, he congratulated the TMNT for saving the world adding "And I thought that was our job" before he and his team fly away.
Fast Forward[]
Silver Sentry is revealed to be the grandfather of the Turtle Titan II. Silver Sentry appears in flashbacks in "Clash of the Turtle Titans" and "The Journal".
Back to the Sewer[]
Silver Sentry returned in TMNT: Back to the Sewer. He can be seen in Mikey's memory in the episode "Identity Crisis" he appears in the episodes "Super Power Struggle" and "Wedding Bells and Bytes".
2007 movie[]
Silver Sentry appears in the prequel children's book Who is the Nightwatcher in a scene where Mikey suspects the Nightwatcher might be Silver Sentry.
IDW[]
In Shadows of the Past, part 2, Michelangelo is thrilled to find a Silver Sentry #1 comic book in the Second Time Around shop.