Okay, so here's what I've got in terms of The Muppets: 70 years in figure form. Bear in mind most of these are from Palisades as that's what my collection consists of for now.
1 Rowlf The Dog, from The Muppet Theater Backstage Playset (associated with if not outright part of Series 9).
2 Lew Zealand (Series 3).
3 Pops the Doorman (Series 9).
4 Skeeter, will now think of her in her adult form thanks to The Muppet Show Comics: Family Reunion (Series 3 Scooter custom base figure).
5 The Male, Female, and Baby Koozebanian Creatures, pack-ins with Koozebane Kermit (Series 4).
6 Wayne and Wanda, my best plausible custom base options are Series 3 Scooter for Wayne and Pigs in Space USS Swinetrek Playset First Mate Piggy for Wanda. Is there a better option for Wanda with what was made available?
7 Mo Frackle (Series 1 Kermit The Frog custom base figure).
8 Yolanda the Rat (Series 4 Rizzo the Rat custom base figure).
9 The Swedish Chef, either Swedish Kitchen Playset (TMM) or Classic Swedish Chef from Series 9.
10 Bernard the Ghost, pack-in with Uncle Deadly (from what I call Series 10).
11 Zoot (Series 3).
12 Gene the Gold Behemoth, custom sculpted figure made by fellow forum member ZootTheSaxman.
13 Animal, from Electric Mayhem Bandstage Playset (Series 2).
14 Walter, either Palisades Sesame Street or NECA Ultimate Volume 1 or even NECA Toony Television Classics Ernie custom base figure.
15 Link Hogthrob (Series 4 as his Pigs in Space persona).
16 The Ghost of Christmas Present (Mini Muppets PVC's Wave 2 Set 4 based on TMCC).
17 The Singing Food: Red Tomato #1 and The Avocado pack-ins with Statler (S6), The Carrot and Red Tomato #2 pack-ins with Waldorf (S6), The Banana and Green Tomato pack-ins with Classic Swedish Chef (S9), and The Cabbage, Eggplant, and Scallion pack-ins with Rainbow Connection Kermit (S10).
18 Robin the Frog, pack-in with Rainbow Connection Kermit (Series 10).
19 Crazy Harry (Series 2).
20 Thog (Mini Muppets PVC's Wave 1 Set 2).
21 Nigel the Orchestra Conductor. Which would be the better custom base option, Palisades Jim Henson Muppet or S1 Kermit The Frog?
22 Janice (Series 5).
23 Bubba the Rat (Series 4 Rizzo the Rat custom base figure).
24 Camilla the Chicken, pack-in with The Great Gonzo (Series 5).
25 Floyd Pepper (Series 2).
26 Polly Lobster, pack-in with Captain Abraham Smollet (Series 7).
27 Dr. Bunsen Honeydew (Series 1).
28 Beaker, from Muppet Labs Playset (Series 1).
29 Pepe the King Prawn (Series 5).
30 Mildred Huxtetter (Series 8 Sam the Eagle custom base figure).
31 Constantine (Series 1 Kermit The Frog custom base figure).
32 Dr. Teeth (Series 1).
33 Rizzo the Rat (Series 4).
34 Joe the Legal Weasel. Which would be the better custom bse option, S5 The Great Gonzo or S7 Johnny Fiama?
35 Bean Bunny (Diamond Select Toys Series 1) which I weirdly think would fit.
36 Dolores the Trombone Player, would a Series 9 Lips be a viable custom base figure option?
Will keep adding as more characters get revealed.