Ah,
The Avengers, the show where no one even remembers what they started out trying to avenge anymore.

I think all but 1 of the episodes with the original lead were wiped anyway.
I also kick myself for not thinking of Barnabas Collins. It got to the point where the DVDs initially avoided releasing any of the pre-Barnabas episodes. (5 years later, they finally released the 1st 209 episodes under the title
Dark Shadows: The Beginning.) And, of course, the recent movie remake was all about Johnny Depp as Barnabas.
I suppose the big 4 in this category would be Barnabas Collins, Fonzie, Steve Urkel, & John Steed.
I've never seen
Blake's 7. It's never been released in the U.S. It makes me feel all left out when the British people get to talk about it.
Wesley on Angel. He started off as a slapsticky comic relief character who would spout exposition about the monster-of-the-week. By Season 3, he'd become a serious hero. Then, after he got himself thrown out of Angel Investigations for kidnapping Angel's son, he became a shotgun toting basass! His dominance of the series became even more pronounced during the 5-part arc in Season 4 when Angel turned evil.
It didn't last. After everyone got their memories erased in Season 5, Wesley took a step back. He became an exposition-focused supporting player again. But Season 4 could just as well have been called Wesley instead of Angel.
I started watching Angel during the Jasmine arc so you can imagine my surprise when I finally got around to watching from the start and seeing Wesley's introduction
Yeah. I didn't start watching until the Pylea arc in Season 2. By that point, Wesley had stopped being such an overtly comic character. Going back, it's really wierd, especially since his more physical style of humor is very unique for a Joss Whedon series. He was more over the top buffoonish than pretty much any other character he's ever written. Interestingly, even as late as Season 3, the writers still hadn't completely dispelled themselves of that image of him. The DVDs include a deleted scene of Wesley doing this broadly comic ballet fantasy sequence in "Waiting in the Wings."
Worf took over TWO shows! And horned in on the last TOS movie!
I wouldn't say that. Worf always remained squarely a part of the ensemble. Even when he joined the
DS9 cast, he still didn't get any more screentime or plotlines than O'Brien, Bashir, Kira, or Odo. If anything, there are some episodes, in Season 4 especially, where his part seems nearly microscopic.
Niles on Frasier. Season 1 was very much Frasier's show. But from Season 2 onwards, it was more Frasier & Niles as a double act. This became more pronounced as the series went on. There are some later episodes where we spend more time in Niles' apartment than in Frasier's apartment. There are some episodes ("Moon Dance," "Head Game") where Frasier hardly appears at all and the episode is entirely about Niles.
To be entirely fair, however, many of these episodes coincided with Kelsey Grammer being in rehab / jail / having extended appearances in court / etc.
Oh, I know. IIRC, "Head Game" was originally written for Frasier but he was either in jail or doing court mandated community service at the time. As for "Moon Dance," I think that episode was specifically written for Frasier to have a minimal role because it was the first episode that Kelsey Grammer directed. But I doubt Grammer's legal troubles explain the heavy emphasis on the Niles/Daphne arc in Seasons 6 & 7.
I didn't watch Homicide, but didn't it go from an ensemble to the Andre Braugher show?
Not really. He was the critical darling that got all the press & awards attention but the show always had major screentime going on for the other characters, especially Kellerman & Lewis.
If anything, the character that seemed to explode as the fan favorite was Munch. After all, the 1st
Law & Order crossover they did featured Pembleton & Bayliss (the ostensible leads to the extent that
Homicide had such a thing). But the two later
Law & Order crossovers they did seemed to exist solely as an excuse to watch Munch & Briscoe snark off of each other.
I'd argue that even now, Xena is more popular than Hercules.
Very true. This is partly because Lucy Lawless is awesome and Kevin Sorbo is an idiot. But also, never underestimate the fervor of a committed lesbian following. (Doccubus!!!!!

)
Surprised no one has mentioned Seven of Nine yet.
Wasn't she meant to be a main character from the moment they first introduced her?
No more than Paris, B'Elanna, Chakotay and Kim, I think.
But she firmly stepped into the footsteps of Spock, Data and The Holodoc.
It could be argued it was pushed by the producers after she was introduced, though, and not simply because of fan reactions.
I would very much argue that. Seven became a major leading character on the show long before fans had a chance to react to her. If anything, the Doctor was the breakout fan favorite there, which is surprising because it seemed to take a while. He'd been a regular on the show from the beginning but didn't really start to rise above the pack until Season 5. I suppose it just took that long for the writers to really become comfortable using the mobile emitter on a permanent basis.