There will always be some actors that will be remembered for that one defining role. No matter how many films or TV shows they star in, none of those performances will ever match the one that made them a star in the first place. It takes a truly special character - and show - to produce a role that can never be bettered no matter how hard you try.
Of course, some actors do achieve the goal of delivering bigger and better roles throughout their career. Despite making his mark as Shane in The Walking Dead, Jon Bernthal has delivered a mesmerising performance as Frank Castle (AKA The Punisher) in Daredevil. And Amy Acker did the seemingly impossible after playing Fred in Angel; her performance as Root in Person Of Interest is a joy to watch.
Sadly that doesn't happen for everyone. Actors might move on from the shows that made them a star to appear in other successful TV shows, but there is no denying that their new character just isn't as good as the last. Here are ten TV actors that never bettered their original role...
10 Dulé Hill (The West Wing)
There is clearly an argument that none of the main and recurring cast of The West Wing are ever going to get a role as amazing as the characters they played on that show. Is Allison Janney ever going to beat C.J. Cregg? Will Martin Sheen ever surpass President Bartlett? Very unlikely, though like the majority of the cast, The West Wing was not their first major TV gig.
Dulé Hill was one actor, though, whose profile was exponentially raised by his role as Charlie Young in The West Wing. The up and coming Presidential aide became a key member of the show, a morally sound young man who entered into a relationship with Bartlett's daughter and became a son in all but name to the Commander in Chief.
Post The West Wing, Hill played Burton "Gus" Guster for 120 episodes of Psych and has had several TV and film roles, but none close to matching Charlie Young. And yes, Gus from Psych might have been a very fun and very different character to Charlie, but wasn't there a point at which he started getting plain creepy?
9 Gillian Anderson (The X Files)
Gillian Anderson was a relatively unknown when she was cast as FBI Agent Dana Scully in The X Files, but she quickly demonstrated that she had the depth and range to make Scully an engaging character over nine seasons and two movies. The strongest actor in the show (sorry David Duchovny), she demonstrated her ability to be funny, deliver power-house performances in a number of emotionally-wrought episodes and quickly became a leading female role model on the small screen. It was clearly apparent that she was the strongest performer when The X Files returned to TV screens this year.
And that isn't to say Anderson hasn't had some great TV roles since The X Files ended. She commanded every scene as Lady Dedlock in The Bleak House and Miss Havisham in a TV adaptation of Great Expectations. And in recent years, she proved she be an engaging ice queen, delivering riveting performances as Stella Gibson in The Fall and Dr. Bedelia Du Maurier in Hannibal.
All amazing performances, but when Anderson defined herself as Dana Scully and proved she could carry the show even when her co-star Duchovny left. It is a role she will never beat and we hope to see return again in the future.
8 Maisie Williams (Game Of Thrones)
Okay, so perhaps it's a little early to call this, but given Maisie Williams' performance as Arya Stark in Game Of Thrones over the last five seasons, is there any character that she could deliver that would be as good as this one? A phenomenal child actor to young adult, Williams has riveted audiences and gone head to head with some acting greats - remember her scenes with Charles Dance's Tywin Lannister in season two?
She has had a couple of good acting gigs since she rose to fame in Game Of Thrones; tough and vulnerable Casey in TV movie Cyberbully, and most recently as immortal Viking Girl Ashildr/Me in Doctor Who, where she regularly matched wits with the awesome Peter Capaldi. But even in Doctor Who it felt as if there was some magic missing from her performance - despite the drama and tragedy of the girl who loses everyone over the centuries, she never quite matched the heartache of Arya Stark.
It's the same rule that probably applies to many of the actors in Game Of Thrones; there is such a rich array of characters, will they ever play someone as amazing after the show ends - of their character meets a brutal and bloody end?
7 Alexander Siddig (Star Trek: Deep Space Nine)
Dr Julian Bashir began Star Trek: Deep Space Nine as an intelligent and very eager young Starfleet officer who was both irritating and dull in equal measure. But over the course of the show, he developed into a fascinating character; the result of genetic engineering, inducted into secret black ops intelligence program Section 31 and proving to be a powerful hero in the war against the Dominion. Oh and considering holodeck episodes were traditionally bad, his James Bond spoof stories were a lot of fun.
Star Trek: Deep Space Nine was the first major TV gig for Alexander Siddig and like many actors on the show, those seven years gave him a rich character to develop that has never really been bettered. Siddig has continued to take on recurring roles in some high profile TV shows, from 24 to Da Vinci's Demons, and British cult shows Primeval and Atlantis.
But none of these roles, not even Doran Martell in Game Of Thrones, has ever matched his work on what many view as the best Star Trek show of all time.
6 David Anders (Alias)
David Anders is no stranger to television; he is currently starring as Blaine DeBeers in iZombie, recurring as Dr. [Victor Frankenstein] Whale in Once Upon A Time and had previous roles in The Vampire Diaries, 24, and Adam Monroe in two seasons of Heroes. But no character has come close to beating his first major role as Julian Sark in Alias.
Sark was a fantastic character - a recurring villain for Sidney Bristow without being outright evil, he arrived late in season one imbued with charm and the natty ability to be one step ahead of the heroes every time and quickly emerged as one of the best characters in the show. And considering the show featured amazing characters like Arvin Sloan, Jack Bristow and Irina Derevko, that was no mean feat.
Arguably the same could be said for Victor Garber's Jack Bristow. He had had a long career in TV and film before Alias but it was his character on this show that really put him on the TV map. And Jennifer Garner, who despite moving into a film career after headlining Alias, never really found a role as engaging as Sidney Bristow...
5 Sarah Michelle Gellar (Buffy The Vampire Slayer)
Talking of TV leading ladies who failed to find bigger and better roles in the movies, we have Sarah Michelle Gellar, who will always be known to audiences world-wide as Buffy Summers. She nearly didn't make it on the list because she had already played the character of Sydney Orion Rutledge in teen soap opera Swans Crossing and Kendall Hart in All My Children. But it is for Buffy The Vampire Slayer that she will always be remembered.
Over seven seasons, Buffy Summers saved the world - a lot. Thanks to Joss Whedon's mesmerising direction and dialogue and some truly momentous television, we saw her battle demon mayors, crazed gods and even her boyfriend - vampire with a soul Angel, who she killed and sent to Hell in the tragic season two finale Becoming. Oh and she died twice. No show will ever give Gellar the depth and range that Buffy The Vampire Slayer did, a role she nailed consistently. Since then she tried her hand at movies, but unlike Jennifer Garner, she never quite made it. And her returns to television with Ringer and The Crazy Ones ended in cancellations after season one and she was never anywhere near as good as she was on Buffy.
It is interesting that she is returning to the TV spin-off of Cruel Intentions, the film that was arguably her most successful project outside Buffy The Vampire Slayer.
4 Alyson Hannigan (Buffy The Vampire Slayer)
Truth be told, you could list almost every actor from Buffy The Vampire Slayer or its spin-off show Angel, perhaps any Joss Whedon show for that matter. His amazing storytelling and electric dialogue makes for an actor's dream. David Boreanaz as arguably never better than he was playing Angel and where has Nicholas Brendon gone after playing Xander Harris?
But there is one actor from these shows that has arguably never bettered herself, despite being one of the most successful stars since the shows ended; Alyson Hannigan. Post-Buffy The Vampire Slayer, she played Lily Aldrin in the hilarious How I Met Your Mother (well the first few seasons consistently anyway) and rose from a minor role to key character in the American Pie series. And like Sarah Michelle Gellar, she had a career before the show, most notably starring in 1998 film My Stepmother Is an Alien with fellow Buffy alum Seth Green.
But like Gellar, it was Buffy The Vampire Slayer that made her a star and she will always be remembered as Willow Rosenberg, the shy best friend of the slayer, turned powerful witch and hero. She was sweet, endearing and witty and everyone loved her - even when she went evil in season six. And most notably her relationship with Tara was one of the most defining TV same-sex relationships of all time. Hannigan will continue to have a good career, but to most she will always be Willow.
3 Summer Glau (Firefly)
Summer Glau got her first role as the Prima Ballerina in Angel season three's Waiting in the Wings and was quickly cast by Joss Whedon on Firefly as River Tam. Over the course of the fourteen episodes, she developed into a brilliant character, a super-powered experimentee/warrior and her emerging backstory was fascinating. It all culminated in the amazing film sequel Serenity, which unleashed her abilities against the dreaded Reavers.
Since Firefly, Glau has had her pick of genre roles, turning up in The 4400, Alphas, Terminator: The Sarah Connor Chronicles, Dollhouse and Arrow. Some of those roles have been amazing, particularly as Cameron in the Terminator series, but no character has come close to matching River Tam.
The tragedy, of course, is that the cancellation of Firefly cut short what could have been a fascinating development of her character - had she had the seven year development of a show like Buffy The Vampire Slayer, River Tam could have emerged as one of the greatest TV characters of all time.
2 Kyle MacLachlan (Twin Peaks)
Twin Peaks was by no means Kyle MacLachlan's first big role, but it was his first foray into television after playing key characters in the film adaptation of Dune and of course David Lynch's Blue Velvet which put him front and centre for the role of FBI special agent Dale Cooper. There is a lot to love about Twin Peaks but MacLachlan was undeniably the star. His line "Diane, I'm holding in my hand a small box of chocolate bunnies" is still one of the quirkiest lines in TV history.
Since Twin Peaks ended in 1991, MacLachlan has found a lot of TV roles, from Sex In The City and Desperate Housewives to How I Met Your Mother and Agents OF S.H.I.E.L.D. And while he has developed a penchant for comedy and played a surprisingly heartwarming villain in S.H.I.E.L.D, no one has come close to matching the role of Cooper, hunting down the killer of Laura Palmer, sampling fine coffee and cherry pie and venturing into the dreaded Black Lodge.
The ending of Twin Peaks is one of the most tragic cliffhangers in TV history so it was a dream to have the show return next year, with Kyle MacLachlan back to play his greatest ever role...
1 Enver Gjokaj (Dollhouse)
Who is Enver Gjokaj you are probably asking? Fans of Agent Carter will recognise him as Daniel Sousa and he has popped in numerous shows, from Dexter to The Walking Dead. He even - as IMDB will claim - had a role in The Avengers but in reality he was a "blink and you'll miss him" cop during the battle of New York. Sousa is probably his biggest role but he isn't the strongest character on Agent Carter despite Gjokaj's efforts. Which is a shame, because given his role as Victor on Dollhouse, he should be a star by now.
Eliza Dushku and Dichen Lachman may have played the dolls Echo and Sierra - with their ability to play new characters each and every week - well, but it was Victor that was truly the greatest actor on that show. Gjokaj played a charming lothario one minute, battle-scarred soldier the next and then transition into a woman in a man's body dancing like the campest gay queen in a club. And his impression of Fran Kranz's Topher Brink was the stuff of legends.
Enver Gjokaj rose to the challenge that Dollhouse set him and then some and yet sadly, it never led to the big starring roles he should have been offered since. Though truth be told, given such a diverse range as he played in Victor, no one has or will ever come close to matching that brilliance.