Outside the guarantees of a contract, there is nothing sure about television. Before that legally binding document is drafted up and signed, there is always the chance that a studio will hire somebody else and leave the other candidate without work. Even after the promises are put into writing, there is no assurance that said contract will be renewed once it expires. Hollywood may be a glamorous industry, but no one ever said it came with job security.

Actors are not exempt from this harsh reality either. Sometimes they are replaced after a few episodes of a show due to negative audience reaction and other times they are fired after already becoming a familiar face to the audience. Whatever the case, the effect each firing and replacement has differs depending on the situation.

For this list, we'll be taking a look at two categories. The first is mid-series replacements that audiences barely noticed. This could mean the replacement happened too early in the series for the first actor to carve their way into audience's hearts or that the actor was on the series for a while and never resonated with viewers. The second category will be mid-series replacements that had a huge effect on the show and couldn't help but draw attention to itself.

So as promised, here are 8 Actors We Didn't Notice Were Replaced Mid-Series And 8 That Were Too Noticeable

Not Noticeable: Lacey Chabert replaced By Mila Kunis On Family Guy

In its infancy, Family Guy was far from the cultural mainstay that it is today. As a result, the characters were not as recognizable and the actors who portrayed them were not so closely associated with them. Lacey Chabert voiced the Griffin Family's black sheep daughter, Meg, for the series' first fourteen episodes.

Ultimately, schoolwork and other scheduling conflicts prevented Lacey from continuing her work on the series and Mila Kunis was hired as her replacement.

Due to the nature of animation, cast changes do not require any aesthetic changes to the actual characters, so most viewers tuned into the next episode without batting an eye when Meg was voiced by a different actress. The biggest reaction anybody gave was no more dramatic than "huh, she's got a different voice now, interesting."

Too Noticeable: Mike Evans By Damon Evans On The Jeffersons

Long before the time such labels existed, Norman Lear's shows often crossed paths and created enough spin offs for his creations to be dubbed "The Norman Lear Television Universe" or "The Leariverse." While it was awesome to see so many characters develop on television for so many years, it also meant that keeping the same actors in those roles would be difficult, and sometimes impossible.

Mike Evans first played Lionel Jefferson on All In The Family and continued in the role when The Jeffersons first aired in 1975.

After the first year of the spinoff Mike Evans left and was replaced by Damon Evans, whose last names are purely coincidence. Mike was so closely associated with the character that he eventually returned in The Jeffersons' fifth and sixth seasons.

Too Noticeable: Krysten Ritter by Laura Clery, Lindsey Broad, And Finally Kate Micucci  On 'Til Death

Sometimes writers find clever ways to work cast changes into a show. 'Til Death chose to do it in an insane way that worked well for the surprisingly irreverent multi-camera sitcom.

Eddie and Joy Stark's daughter, Allison, was played by Krysten Ritter in a recurring role during the first two seasons. Then, Laura Clery had the role in season three, still only sporadically showing up. In the final season, the daughter became a main character whose actress was again changed to Lindsey Broad, and then finally Kate Micucci.

Rather than ignore the replacement, the writer's opted to make it a gag on the show. During the final season Allison's husband, Doug, starts to believe he is living in a sitcom and he immediately acknowledges when his wife is all of a sudden a different woman. It's rather clever to point out the elephant in the room before anybody else does.

Not Noticeable: Sharon Wilkins By Sherri Shepard On 30 Rock

With a total of seven seasons under its belt, 3o Rock went through a variety of changes throughout its run. Despite the changes, or maybe because of them, the show remained a strong and creative presence on primetime television right up until the end.

Some of these changes were immediately apparent to audiences, while some of them slipped under the radar.

One such instance of the ladder is the casting of Tracy Jordan's wife, Angie. In the character's debut appearance in the episode "Jack the Writer" she was played by Sharon Wilkins. However, for reasons that are unclear, all of the character's subsequent appearances were portrayed by Sherrie Shepard. Is Sharon Wilkins bitter about being replaced on such a legendary show? It's difficult to say if there will ever be an answer to that question.

Too Noticeable: Dick York By Dick Sargent On Bewitched

Bewitched is easily one of the most iconic and recognizable television shows from the 1960s. it's a safe bet to say that, even more than forty years after its initial run, an episode of the sitcom is playing at least once a day somewhere on some channel in syndication.

When a show lasts as long as Bewitched does, there are bound to be casting shakeups.

For this show, it happened when the male lead, Dick York, was no longer able to perform due to debilitating back pain. After the fifth season, York left the show to focus on his recovery and was replaced by Dick Sargent. While the change was definitely noticeable and Dick York was missed, the change did not spell doom for the show and it remained on the air for three additional seasons with Dick Sargent playing the witch's husband.

Not Noticeable: Alexandra Krosney By Amanda Fuller On Last Man Standing

In a not all too atypical situation, Last Man Standing was loved by audiences and panned by critics. Even after its cancellation in 2017, it is still living on in syndication and streaming.

Viewer reactions were so positive that they did not seem to pay any attention when one of the major cast members was replaced after the first season.

Beth Baxter, the oldest daughter of Mike Baxer (Tim Allen's character), was played Alexandra Krosney in the show's premier season. When it came time for the hit series to start up its second season, Alexandra was not brought back and Amanda Fuller was now playing Beth. While Beth Baxter was a main character on the show, the change in actress did nothing to derail the show's success among audiences.

Too Noticeable: Richard Thomas By Robert Wightman On The Waltons

The Waltons was classic wholesome television for the whole family to enjoy. While the show was about the entire titular family, much of the focus was placed on the oldest son, John Boy. Richard Thomas had the role of John Boy for the first five seasons until the character temporarily leaves the show for the next two seasons. John Boy eventually returned in the middle of the eighth season, but played by Robert Wightman.

Audiences had come to associate Richard Thomas with John Boy, so the change was a little hard to swallow for some.

While Robert Wightman remind in the role for the rest of the series and for three television movies, Richard Thomas did eventually return to the part for A Walton Thanksgiving Reunion and the two following films.

Not Noticeable: George Morgan By William Christopher On M*A*S*H

The characters on M*A*S*H were so well developed that they genuinely felt like real people and, more importantly, like they could be a good friend. One of the few characters to remain in the 4077 for the show's entire run was the unit's chaplain, Father Mulcahy. William Christopher is immediately recognizable in the part, but he did not play the character in every episode.

Excluding Rene Auberjonois's portrayal in of the character in the film, the pilot episode of the iconic show actually featured a different actor in the role.

George Morgan was the first actor to play Father Mulcahy on television, but was immediately replaced by the now very familiar William Christopher. It's hard to say if the character would have been as beloved if George Morgan had not been replaced, and the world will never truly know.

Too Noticeable: Laura Allen By Tippi Hedren On The 4400

The 4400, from the very start, was shrouded in mystery. As the show went on, events only became stranger and there were consistently more questions than answers. Unfortunately, viewers were never given answers as the show was unceremoniously canceled after four seasons. Fortunately for the writers, the mysterious nature of the show meant they could actually explain mid-series replacements.

When Laura Allen left the show after its second season, the producers were forced to get creative in order to work her exit into the show.

The solution was that her character, Lily, was to mysteriously age several decades. After this event took place, Lily was played by veteran actress Tippi Hedren. While the arc pointed out this casting change, it also seamlessly weaved it into the narrative.

Not Noticeable: Julie Newmar By Eartha Kitt On Batman

The 1960s Batman television series is a one of a kind creation. On the surface, it appears to be mindless fun for kids, but underneath there is a plethora of comedy for adults to enjoy. This creative format has seen the show stand the test of time and find new fans with each subsequent generation of comic book nerds. While adult fans of the series noticed casting changes, the other, much younger half of the fan base did not see the actors past the characters and did not think twice if their favorite characters looked a little different.

One such example of this is Catwoman, who was initially played by Julie Newmar in the first two seasons before being replaced by Eartha Kitt in the final season.

As an added bonus for this list, Catwoman was also played by Lee Meriwether in the 1966 film.

Too Noticeable: Lisa Robin Kelly By Christina Moore On That '70s Show

For most of the entries on this list, cast members are replaced for business reasons or because the actor leaves the show to pursue different opportunities either in television or film. Unfortunately the departure can sometimes be more sorrowful, like with Lisa Robin Kelly on That '70s Show

Lisa played Laurie Foreman on the popular, nostalgia driven sitcom for three seasons. However, a serious drinking problem caused her to leave the show.

The actress played the character in a few sporadic appearances, but was ultimately replaced in the sixth season by Christina Moore. Christina Moore only played the character for six episodes, as perhaps the show runners ultimately decided that it was better for the character to not be in the show at all rather than played by a different actress.

Not Noticeable: Phyllis Coates By Noel Neill On The Adventures Of Superman

The Adventures of Superman was a landmark show for several reasons. Its early seasons mixture of mystery stories and Superman was a ingenious format for the superhero and guaranteed that it would not be forgotten for many generations. George Reeves is perfect as the titular character, Jack Larson is, to date, the best Jimmy Olsen, and Noel Neill is the definitive Lois Lane, though she was not always in the role.

For the show's first season, Lane was played Phyllis Coates. However, when the show was ready to be renewed, Phyllis Coates was no longer available.

Fortunately, the answer to this conundrum presented itself clearly as Noel Neill was available and had in fact already played the character in the 1948 Superman serial. Phyllis Coates, while great in her own right, never felt like the definitive Lois Lane.

Too Noticeable: Steve Burns By Donovan Patton On Blue's Clues

In some examples on this list, children would not have noticed when a character was played by a different actor. However, sometimes young viewers become very attached to a character on a show, like Steve Burns on Blue's Clues.

Steve was the host of the children's program for more than six years and was a huge hit with the kids and their parents.

His hosting style was unlike anything educational programming had seen before. Eventually Steve decided to leave since he was not intent on being a children's TV host for his whole life. He was replaced by Donovan Patton, who was a different character, but ultimately served the same role. To alleviate children's shock at the change, the show incorporated the change into the show with Donovan taking over after Steve left for college.

Not Noticeable: Jon Kricfalusi By Billy West On The Ren And Stimpy Show

Fans of The Ren and Stimpy Show will forever owe a debt to Jon Kricfalusi. As the cartoon's creator, he is responsible for introducing a whole generation to humor they may have been a little too young for. With that being said, his voice could not compare to the masterful work done by Billy West.

Jon played Ren for the early years of the show until his radical, barely safe for children comedic style caused him to get fired from the series.

After this, Billy West, who already voiced Stimpy, also started voicing Ren. West is objectively one of the best voice actors out there, so while it is lamentable that Jon was let go from a show he created, the voice of his character was left in good hands.

Too Noticeable: Every Regeneration On Doctor Who

David Tennant as Tenth Doctor in Doctor Who

One essential aspect of the long running science fiction series Doctor Who is the inevitable transformation the main character undergoes. This story element sets it apart from most other shows and enables it to continue on almost indefinitely, as long as the ratings hold up.

While an essential part of the series' plot, this concept actually rose up out of necessity.

In 1966, William Hartnell, who played the first doctor, departed the series after suffering from severe health problem and having disagreements with the new producers. To remedy this, the show introduced the concept of regeneration. Ever since then, the idea has a been mainstay of the long running British show. While originally done to write an actor of a role, the Doctor's regeneration has helped keep Dr. Who fresh and exciting.

Not Noticeable: Philip Bruns Replaced By Barney Martin On Seinfeld

If aliens visit earth thousands of years after mankind is extinct and they stumble upon Seinfeld, humanity will be extremely lucky to have left this show as its immortal legacy. These days, all of the characters are cultural icons, but when the show was on the air, it took a little while for much of the supporting cast to fall into their rightful place with the appropriate actors. A prime example of this is the character of Morty Seinfeld, the titular character's father.

Philip Bruns portrayed the character in his only appearance in the first season, but was subsequently replaced by Barney Martin.

Since the show's format had not yet been fully established in its first season, nobody's attention was piqued when Seinfeld's dad was played by a different actor the next time he showed up.

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What other mid-series replacements can you think of? Let us know in the comments!