What shows made a character addition that worked?

Often, a TV show will add a character to boost low ratings, get worse as a result and die soon afterwards. What are the exceptions, shows that actually got better or at least maintained quality while adding a major recurring character?

I can only really think of one offhand: Step By Step, and it worked only because Bronson Pinchot was so damn good as Jean-Luc Rieupeyroux.

Was Pinchot in the credits or was he just a recurring character? The reason I ask is because Star Trek: Deep Space Nine got better with the addition of Worf from Star Trek: The Next Generation as part of the cast but it also continued to improve with its serialization and extensive use of recurring characters that often had more screen time than some of its stars.

Buffy the Vampire Slayer. Spike.

I didn’t watch it, but apparently The Practice got REALLY good in its last season when it introduced Alan Shore (James Spader) and Denny Crane (William Shatner). Then The Practice ended and those two guys spun off into their own show, Boston Legal, which IS really good.

The X-Files. X.

MASH* replaced every major character except Alan Alda, Loretta Swit, and William Christopher. And it was solid up until the end.

“Cheers” added Frasier and Lilith as major characters after a few seasons. That worked out really well.

Angel - Wesley; Gunn; Fred

Star Trek - Chekov;
(“Eeee! Now say ‘nuclear wessels’!” /Futurama)

Mystery Science Theater - Complete Cast change;

Married with Children added Ted McGinley as Jefferson Darcy. That was probably the best work he’s ever done (not saying much), and the show lasted despite his presence

Interesting aside:
He played a pirate captain in one of Peg’s dreams prior to being cast as Jefferson. I think he had one other show, but I can’t recall off the top of my head.

Voyager springs to mind with the addition of 7 of 9.

The Healey boys: Mark and David on Roseanne.

Does Jefferson D’arcy and 7 of 9 fit the OP? Those characters weren’t really additions, so much as replacements for Steve and Kes.

ER is another show that has turned over virtually the entire cast. I think the addition of Kerry Weaver (Laura Innes) improved the dynamic of the show (at least until the whole show went to hell, but that’s another thread.)

Norman Buntz (Dennis Franz) gave as big a shot of energy to Hill Street Blues as any character ever added to any show.

The addition of Georgette (Georgia Engel) to the Mary Tyler Moore show is generally regarded as helping to fill out the Ted Baxter character, thus strengthening the show.

Poochie!!!

Ok maybe not…

Christopher Lloyd as Jim Ignatowski in Taxi wasn’t added as a regualr cast member until the second season. He did made an appearance as “Reverend Jim” in the first season, though.

The pirate captain dream was after McGinley joined the cast. They did bring back David Garrison to play the singing pirate. It was a hoot.

Barney Miller added Dietrich during the second season. In the first season, he played a prisoner who was a priest.

MAS*H was not just solid, but enormously improved by the replacement of Frank Burns (Larry Linville) with Charles Winchester (David Ogden Stiers.) Burns was a silly, irritating character whose stupidity defied belief even in a comedy; Winchester was a more rounded, interesting and believable foil.

But that’s a REPLACEMENT, not an addition, I guess.

I’ll take your word on that. I do remember McGinley appearing prior to his Jefferson days. Time to sit down with seasons 1 and 2 and figure out where. I’ll be back to you when I can squirrel away 24 hours of continuous TV time.

adam yax, I was considering whether he counted as a replacement or an addition. I opted for addition, as they left Marcy as abandoned for a season, although I won’t defend that point aggressively.

He appeared on Happy Days toward the end of its run, IIRC playing a teacher (I think the hook was that Fonzie became a shop teacher and so they introduced other faculty members) and joined The Love Boat toward the end as the ship’s photographer.

Replacing Stephen Hill as star of Mission: Impossible by Peter Graves was a big success. Most people don’t even realize Mr. Phelps was not the original leader of the IMF (though I prefer the first season with Hill).

In addition, Martin Landau was not part of the original IMF cast. He guest starred in the pilot, and his character worked so well that he continued to guest star – in just about every episode. For the first two seasons, at least, he was not officially part of the regular cast.

The addition of Little Ricky to I Love Lucy didn’t hurt ratings at all.

That was their “It’s a Wonderful Life” Christmas episode. McGinley played Peg’s husband in the alternate life.