Basic Level: User can only travel seconds backwards/forward in time.
Advanced Level: User can travel minutes backwards/forward in time.
Expert Level: User can travel hours backwards/forward in time.
Master Level: User can travel days or several Weeks backwards/forward in time.
Ultimate Level: User can travel months/to several years backwards/forward in time.
Absolute Level: User can travel decades, centuries, or even millennia backwards/forward in time.
May cause the Butterfly Effect; for one cannot change the way things are without destroying what it was.
The person's attempt to time travelling may be futile due to the Grandfather Paradox preventing them from achieving their goal in altering the past and future.
May be unable to move to a different location spatially, and instead just end up in the same location in a different timeline. Telefrag is possible as a result.
Protection conjecture, a cause that prevents the change of the past, could interfere with the Time Travel in some cases. If not and the past is change, results in the present time, before the travel, can have unwanted results.
Time travel may separate the user from space, which would leave them entrapped within time, rendering them biologically immortal, intentionally or not.
Abuse and misuse of time travel may result in one's mind losing track in time, causing the body to age but the mind to remain young.
Because of the complexities and potential dangers, time travel is sometimes considered a taboo and against the law of nature, and even outlawed by some governments.
Cannot interfere in certain matters concerning the flow of time and space.
It's not known if the future is protected by the same cause the past is (see Precognition for more info how changes to the future could be prevented).
May distort the space-time continuum in exchange for traveling.
May only be able to transport living tissue through time.
May only be able to go either backward and forward in time.
May only be able to travel the duration of their own lifetime.
Time travel to the past may create an alternate timeline, in order to prevent changes to affect the original time. This means that the past would branch off into a new dimension of time, while the present timeline would continue as though nothing affected the past. This prevents intended changes.
Professor Paradox (Ben 10) used his thorough understanding of the space-time continuum to travel through time.
Temporal Boomerangs (Ben 10) allow the users to take one five-minute round trip back in time.
Gwen Tennyson (Ben 10) time traveled to pick up younger Ben & Gwen to teach older Ben to be not arrogant ...
... and later she went back in time to prevent Kevin's mutation.
Time Cycles (Ben 10) have the capability to travel through space and time, giving the user instantaneous travel.
Clockwork (Ben 10)
Chronoscaphe (Blake and Mortimer)
Uncle and Jade (Jackie Chan Adventures) seeing Jackie go back in time.
The Time Sphere (Futurama) opens up when someone speaks the code, and takes people back to the past at the cost of any time-duplicate paradoxes dying.
Farnsworth (Futurama) invented a time machine that allows the riders to travel forward into the future only, to prevent past paradoxes.
The Phoenix Gate (Gargoyles) enables the user to travel through time and space.
Blendin (Gravity Falls)
Toyman (Justice League) created an Energized Tachyon Stream that sends anything it hits to thousands of years to the future.
David Clinton (Justice League) using his Time Belt to warp and control through space and time, becoming the self-proclaimed "Undisputed Master of Space and Time".
The Iron Doom (Lego Ninjago: Masters of Spinjitzu) time traveling through the time vortex…
…before landing forty years in the past.
The Phoenix Force (Marvel Comics) can bend itself into the space-time continuum to travel through space and time.
Magik/Illyana Rasputina (Marvel Comics) using lightdisk.
Nathaniel Richards/Iron lad's (Marvel Comics) armor can time travel.
Franklin Richards (Marvel Comics)
Starlight Glimmer (My Little Pony: Friendship is Magic) used Star Swirl the Bearded's time spell scroll to open a time portal over the Cutie Map to travel back in time.
Renet (Teenage Mutant Ninja Turtles)
The Sands of Time (Xiaolin Showdown) allows those who use it to travel through time and alter it.
First appearance of the aptly named "Enigma" (Girl Genius), also called Muse of Time, who has the ability to travel through time seemingly at will.
Professor Zapotec and Professor Marlin (Mickey Mouse) can send Mickey and Goofy through time and space via their time machine, and occasionally one of them travels with them.
Time Machine (Meet the Robinsons)
Tom Turbo (Tom Turbo) can travel through time using one of his 111 tricks.
Clockwork (Danny Phantom) is the Ghost of Time, making traveling through time an easy feat for him.
Clockwork has Time Medallions (Danny Phantom) that allow ghost or humans to exist outside of time and time travel.
The Time Booth (The Adventures of Jimmy Neutron: Boy Genius)
Time Tape (Gravity Falls)
Dranakis Threshold (Chaotic)
Duggee's Time Machine (Hey Duggee)
Nina Crocker/Timezone (Static Shock) main ability is to Time Travel but it messes up the space-time space-time continuum and she always used it intentionally.
Trunks' (Dragon Ball) time machine allows him to travel to the past.
Time Rings (Dragon Ball Super)
Ultear Milkovich (Fairy Tail) after becoming one with Time itself became a time traveler of the temporal world.
Kagerō (Flame of Recca) using Jikuryūri, which allows her to travel through time via a portal, but it traps her within time itself, rendering her immortal.
Kurei Mori (Flame of Recca) using Jikuryūri to open a time portal in space, but cannot become immortal so he does not have to worry about being trapped in time.
The Bone Eater Well allows Kagome and InuYasha (InuYasha) to travel between the 500 years of Sengoku and current eras.
Seiryu (Magic User Kurohime) is the wind spirit, and can manipulate space-time the wind just floats through it freely, even allowing others to travel back through time.
However, when Pryce (Pokémon Adventures) forced Celebi to travel back in time, it adversely caused temperature dropping to absolute zero and the world completely freezing.
Sailor Pluto (Sailor Moon) is the guardian of the Door of Time.
Backlander (Dinosaur King)
Karasuki (Boruto: Naruto Next Generations) is an artefact that takes the shape of a turtle-like device when activated, used only by the Ōtsutsuki Clan members only, that allows them to travel through time.
Kurumi Tokisaki (Date A Live) can send others or herself into the past using her twelfth bullet Yud Bet, traveling through time.
The MTD (Call of Duty: Black Ops) became capable of time travel after the Element 115 power source of the Wunderwaffe DG-2 overloaded the device.
Pokey (Earthbound) had abused Time Travel to learn PSI, and from a youthful boy (right), he became an elderly immortal (left) due to being trapped in the current timeline.
Kessler (Infamous) traveling back in time.
Time Hole (Mario & Luigi: Partners in Time)
Celebi (Pokémon) lives up to its classification as the "Time Travel Pokemon".
Dialga's (Pokémon) "Roar of Time" can transport others back in time by distorting it, among other effects.
Sonic and Shadow (Sonic the Hedgehog) crossing their "Chaos Control" to create and travel through a space-time rift.
Mephiles the Dark (Sonic the Hedgehog) can travel through time without a Chaos Emerald.
Solaris (Sonic the Hedgehog), being the Sun God of Time, can exist and travel through all times.
Time Eater (Sonic the Hedgehog) can create "Time Holes" to travel through time.
The Time Eater (Sonic the Hedgehog) opening Time Holes to utilize its Warping Arm Attack, which appears at a specific point in the future
Beyond the Door of Time (The Legend of Zelda) Link can travel between seven years forward and back.
By pulling the Master Sword, Link (The Legend of Zelda) can travel forward seven years and vice-versa.
By playing the Song of Time, Link (The Legend of Zelda) can return to the beginning of the three day cycle.
When Link (The Legend of Zelda) plays the Harp of Ages, he can travel through time depending on the tunes.
There are two Gates of Time (The Legend of Zelda) that allows the travelers to go back in time.
Time Traveler (Valkyrie Crusade) lives up to her name.
ClockMan.EXE (Rockman.EXE Operate Shooting Star) is NetNavi that can travel trough Time.
The Charmed Ones (Charmed) time traveling to the future...
... and to the past
Billie Jenkins (Charmed) can use her projection power to travel through time.
Piper and Leo (Charmed) use Cupid Ring to travel through time.
Mel and Maggie of the Charmed Ones (Charmed 2018) travel back in time from the spell call to a restless spirit.
Hermione and Harry (Harry Potter) using the time-turner to travel three hour back.
Zelena (Once Upon a Time) can use the Time Travel Spell to travel through time.
Lucy (Lucy) travels through time.
Flash (The Flash) can move at such Absolute Speed that he can travel through time and space.
Agent J (Men in Black) about to perform the "Time Jump".
The Doctor (Doctor Who) uses the TARDIS to travel through space and time.
The TARDIS (Doctor Who) can travel in both time and space.
Rip Hunter (Legends of Tomorrow) and the legends use the Waverider to travel through space and time.
By manipulating the space-time continuum, Hiro (Heroes) can travel through time.
Kitty Pryde's (X-Men: Days of Future Past) phasing abilities advanced so much that she can phase through space and time, allowing her to send someone's mind to the past or future.
DeLorean Time Machine (Back to the Future)
Jules Verne Time Train (Back to the Future Part III)
Shelby and Cyd (Best Friends Whenever) have a time travel power which makes them move to the past and future by touching each other in any way. This is a special power that no one has ever discovered.
Time Jerker's Time Portal allows both people and objects to travel through time, remotely bring them back from the past or future,...
... or even trap someone like Drex in a Time Warp, where he is floating between times between the past, the present, and the future.
Henry Hart/Kid Danger (Henry Danger) uses the Time Ray, that can send any object and person through time, by pointing and shooting it at Ray Manchester/Captain Man turkey leg.
Sundial World (Kikai Sentai Zenkaiger)
After her ascension to godhood via SCP-001 - A Record (SCP Foundation) Dr. Mary Nakayama gained the ability to travel through time, which she used to save her past self from a suicide attempt.