It’s a tricky proposition to add someone new to the mix of a TV cast. The reasons for adding a character are different and their reception can be largely based on how they are pushed into the limelight. Sometimes new characters are added as bait for a storyline, sometimes they are added to replace characters who have left a show, and sometimes they are last ditch efforts to revitalize a show on life support.
In my experience, the best additions come when you barely know they’re there. By which I mean they start as a guest spot and work their way into Regular status. Shows that rely heavily on chemistry, here I’m talking about the show Bones, must take care to ensure the new character fits with the rest of the cast. The showrunners of Bones have done an excellent job in this regard with the addition of Dr. Sweets (John Francis Daley, also of Freaks and Geeks) into the regular rotation. You don’t want someone dropping in with no segue or transition time, rather you need to let that character build up some trust with the viewership and make it seem like they have always been part of the gang. Admittedly, Sweets was added as bait for a storyline from last season, but they worked him into a great supporting regular. Kudos Bones team.
But there are also times when the addition isn’t so great and these probably outnumber the shining examples. The most infamous of these additions is Scrappy Doo onto the Mystery Machine Team. His spunk was a complete antithesis to his uncle’s famous fear. And Scrappy was really just a letdown altogether. Out of respect for the Doo franchise I won’t even go into Scrappy’s role in the Scooby Doo Movie. Terrible. Suffice it to say, Scrappy never had the PUPPPPPPY POWER! to win over fans.
Another terrible move was replacing Topher Grace on That 70′s Show. The dynamic of that group of teens was what made the show work. And using a guy who I can’t even name off the top of my head to replace someone as well known (in that role, especially) as Grace was a real bonehead move.
All shows are vulnerable to this mania of character pileup, two of the shows I follow most ardently are two of the most character laden shows on television, those being Heroes and Lost. Heroes has created a character car wreck of epic proportions to the point that watching the show requires venn diagrams and family trees. Lost has largely been successful in their regular addition of characters, with one GLARING exception and fans of the show know who I’m talking about (COUGH NIKKIANDPAULO COUGH). But they’ve done such a good job that two of their add-ons have become fan favorites and play critical roles in the canon of Lost mythology.
It’s a mixed bag really and I think a lot of it depends on the show. It’s tougher for comedies to introduce new characters I would think than dramas. But I could be way off base. The list of these failures and successes certainly doesn’t end here.
Do you have a fave/least fave new character?

Although I really like Alyssa Milano – I hated it when she joined My Name is Earl. I like her better as Sam from Who’s the Boss.
I also don’t like the addition of Steven Weber as the guys heading up the FBI Unit on Without a Trace. (I don’t really like Anthony Lapaglia either – he’s weird – but I’m used to him)
I think Everybody Loves Raymond did a great job of adding in new characters!
Bones may have done a good job introducing Sweets, but I do not appreciate their style with the rotating interns this season. Some have been crazy characters, but its hard to pay proper attention to them when you know they’ll be gone the next week.
Fav new character: I thought V.Mars did a stellar job of introducing new characters and blending them with old faves when they transitioned to season 3: the college days.
Least fav: Nikki and Paulo, hands down. Can’t like ‘em when you know they were just introduced to stall the show until it had a timeline.
Does anyone even remember Saved By The Bell pre-Kelly and Jesse? OK, well I do but just a little bit and they are not pleasant memories, although Miss Bliss was appropriately named (HOT). They completed the ultimate goal of a New Characters to a show, that is we have forgotten about the old ones.
P.S. Don’t get me started on Tori!