Interesting bit of trivia (thanks to of all places: 1 vs. 100), Kelsey Grammer is the only actor to have 3 Emmy nominations for appearences on different shows as the same character: Cheers, Wings and Fraiser

Also, looking up on his bio, he also appeared on The John Larroquette Show as Frasier, so that's 4 shows as the same character.

Crossovers:
Wings (1992) and Cheers
John Larroquette Show (1995) and Fraiser




I had read that there was a planned crossover for Quantum Leap and Magnum PI where Sam leaped into Magnum. It apparently was dopped after they thought Magnum PI was going to be cancelled...

Some others:

All in the Family and the Jeffersons
Beverly Hills and Melrose Place

Beverly Hillbillies and Petticoat Junction

The six-part episode where Space Ghost meets The Herculoids, Mighty Mitor.

Magnum PI / Simon & Simon

Because they all hated each other.

I remember seeing a Magnum PI/Murder She Wrote crossover episode.

Makes me wonder if both parts are are included within the season sets of both series. That would be kinda crappy to have to buy the season set of another show just to see the conclusion/beginning to that particular story.

I have to give props to a certain element of this episode but ultimately I just can't get behind it.

The first time I saw it was when I was going through the "X-Files" series on DVD. I had seen every single episode of "The X-Files" leading up to it but had never seen a "Millennium" episode. As an "X-Files" episode it fails because it includes this character you've potentially never seen before and expects you to accept that he has the same amount of screentime as Mulder & Scully.

When I first saw it I was intrigued by Henriksen's performance but I understandably felt like I was missing out, his inclusion wasn't really natural or organic in any way.

Cut to a couple years later. I've bought the "Millennium" episodes (and loved them) on DVD. Season 1 comes out and I burn through it and I'm tempted to watch the "X-Files" episode but I refuse to watch it until after I see season 3. The same thing happens upon completion of season 2 but I remain strong, I want to experience the episode as the end of Frank Black's journey. It's included as an extra feature on Season 3 so as soon as I'm done with the season proper I watch it.

As many people have said, it completely fails to address any of the many specific plot points left dangling at the end of "Millennium" and thrusts the Frank Black character into something fundamentally unlike anything he experienced within his own show.

OK, that said there's an element of success in the episode as it depicts Frank and Jordan Black surviving into the Millennium and that scene is powerful and satisfying as a fan of the characters and their series but ultimately that's just the silver lining to a very dark cloud.

The New Years kiss between Mulder & Scully is similarly satisfying but in the very same way everything leading up to it is very mediocre and half-assed.

Forgot about this one (though I don't consider it "best of" or anything) but there was a crossover between The Pretender and Profiler...

Buffy & Angel crossovers. Most of them were great.

The Jetsons meet the Flintstones

Wasn't there a Full House/Family Matters crossover? I remember Urkel appearing on another show.

Yeah, Urkel was on Full House and Step by Step.

Sesame Street and The Electric Company. For me, the coolest moments ever was when Easy Reader stopped by Mr. Hooper's store and was greeted by Bob.

I agree with the mentioned Angel/Buffy crossovers.

The Batman/Superman animated series crossovers were awesome as well.

With the exception of "Damage" and "The Girl In Question" from season 5 of ANGEL.

Of all the wonderful people from Buffy they could have brought over, they chose Andrew? Hell, Buffy herself was more preferable to me than Andrew, and it's public knowledge I'm not a fan of Ms. Summers herself.

Ugh!

Do all the episodes of Empty Nest/Golden Girls/Nurses that featured some cast members going whatever way count, or would it just be the hurricane story event that would count?

I'll note that Crossing Jordan and Las Vegas have crossed over I think 3 or 4 times now. I can't really comment on the quality of the crossovers, though.

During all the times there were to two Trek series running concurrently (TNG/DS9 and DS9/VOY), I can't think of any standout moment in any of the few crossovers that they did. The best one I can think of is the DS9 pilot with Sisko coming to terms with Picard, but even that felt a little rushed. Am I missing anything?

I liked the Simpsons/XFIles as well.

I didn't like the Simpons/the Critic though. I find the Critic's (Jay?) to be annoying and the show was very unfunny.

I always wanted to see the Simpsons meet Futurama ala the Flinstones meet the Jetsons.

I thought the Girl In Question was great. Then again, I thought Andrew was one of the few bright spots from Buffy season 7 so.....

The upcoming CSI: NY episode has a, from what I saw, one character cross over with Cold Case.

Here we go:

http://www.poobala.com/crossoverlist.html

This just about covers everything....including some stretching here and there. Scroll down a bit to get to the list.

Mad About You and Seinfeld.
I used to watch Mad About You with my wife every week and had never seen an episode of Seinfeld (The first episode I ever saw was the series finale. I've since seen every one in syndication). I remember when Kramer popped up thinking, "So, who the hell is this guy."

Yea looked good from the preview i saw after i watched Cold Case. CSI: NY had been really good this season and so has Cold Case.

Drew Carey/Coach crossing over was one of my favorites of all time. Coach is my #1 fav. show (extremly underrated).

The Pretender/Profiler crossover was pretty good but i don't like the profiler.

Third watch/ER was alright as well.

The Las Vegas/Crossing Jordan crossovers happen all the time to the point that no one really cares anymore.

Actually looking at the list there are alot of great crossovers that i liked.

John Munch has done the most crossovers. He has been in 7 different shows, and is scheduled to appear in a cameo in a French version of SVU

One recent one that really wasnt much of a crossover as just a cool cameo, Mykelti Williamson appeared on the pilot for Raines as an unnamed detective...considering Raines is produced by Graham Yost, and it takes place in LA, Id guess he was reprising his role of "Fearless" from Boomtown

Best crossover to never happen: APO calls on the resources of CTU and teams up Sydney Bristow and Jack Bauer. A Buffy/Veronica Mars or Angel/Firefly crossover would have been pretty cool too.

I wouldn't put this in the "best" category or even the "good" one.

Everybody loves Raymond / King Of Queens