A time traveling superhero is very rare to find in comic books these days. But comic books do have many established heroes that fit the ‘time traveling superhero’ category.
With access to the Speed Force, the Flash gains access to speeds that are well beyond the speed of light. He can empty all civilians from an entire city in a pico-second. He can also run so fast time slows down and at one point, even starts flowing in the opposite direction. The Flash has already used this ability to change the past and create alternate timelines. Flashpoint is a good example.
A very underrated X-Men hero who deserves more love, Kitty Pryde is also known as the Shadowcat. Her phasing ability is well-known. She can phase herself and any person/object she is in physical contact with through any object, no matter the size or shape. But Pryde does have one more ability that was explored in Days of Future Past. She can send her consciousness back in time to her younger self. That is a very nifty way of time traveling. Her ability opened up the potential for further Marvel time travel tales.
In the Marvel comic book universe, no hero is more synonymous with time travel than Bishop. During the Onslaught Saga, the time traveling superhero Bishop travels from the future to the past (and the then present timeline) to warn the X-Men about the grave threat of Onslaught. His words come true and the Avengers and the Fantastic Four are sent to live in a pocket universe for an entire year, leading to the Heroes Reborn saga.
Silver Age Superman
Back during the Silver Age of DC Comics, Superman had some truly Godlike abilities that defy all explanation. One of those abilities was his power to traverse timelines. During that era, Superman was less experienced and too green to be a part of the DC Trinity. Superman was then known as Superboy and he would casually hop from one point in time to another in his stories. He could even take people with him along for the ride. Superman as a time traveling superhero seems absurd now because DC took a lot of time and effort to make his powers as grounded as possible.
The son of Cyclops and Madelyne Pryor – a Jean Grey Clone, Nathan Summers is an Omega Level mutant and time traveling superhero. He has not just one but two modes of time travel. He can uses a special gadget to transport himself as well as his allies to a different point in time. Cable can also use his telepathic abilities to somehow send his astral form back in time. The second method is quite difficult to perform and Cable has only ever done it once. But that does not mean he cannot do it again.
Nathaniel Richards aka Iron Lad has a suit of armor that seems pretty much the same as Iron Man’s. He has traveled to the past and become a part of the Young Avengers. The sole difference between Iron Lad and Iron Man’s suit is that the former has the technology to create temporal divergences. This allows him to manipulate the timestream as he pleases. Nathaniel Richards even has an entire ship that possesses similar time travel technology.
DC was not joking when they said that the Green Lantern Power Ring is the most powerful weapon in the universe. If you have enough willpower, the ring can use it to rip open the fabric of reality. One of the Power Ring’s lesser known abilities is time travel. Hal Jordan has used it to travel to the future, almost as far as the 70th Century. The Ring can also allow a Green Lantern to communicate with people of different timelines.
He is an ordinary man from a future timeline who stole technology from a superhero museum and traveled to the past to become a superhero. His suit has special time travel circuitry that gives him the power of traversing across time. It also allows the time traveling superhero to control the time stream remotely.