I've noticed there was a 4 pages thread on Mattycollector about the possibility of including Octavia in the MOTUC line and I've also read Scott's answer to fan's question in the other thread about it.

Lot of fans quoted my research and theories about the subject.
But, I ask that you don't use my theories and research to challenge Mattel.
I only post it for historical entertainment.
Only Mattel knows the Legal status of past and present characters.
I am certain Mattel wants these characters too. We must trust them to handle character rights on their own.

Copyrights issue are a complicated matter.
A piece of paper with info about who first drew a character does not tell us the whole story.
We do not know the contracts Mattel has/had with other companies.
So we can only speculate only on the origins of this art.

MOTU is an almost 30 years old property. Lot of the original art is all over the place, and it may happens that, from time to time, fans or collectors came across images or informations people currently at Mattel don't have or haven't seen before (for example the Gygor prototype).
When we find this art, the best we can do is post it and hope it is maybe helpful to Mattel.
But only Mattel know if these images add valuable info to the rights status of certain characters. And we have to wait and see if they do. They are not obligated to tell us these things.

Here are my historical design theories, all in once place for your entertainment.

First, there is the Filmation Model Sheet AlessandraF posted on Matty's forum.
Model Sheet are the characters model turnarounds used as reference by the animators during the production of a cartoon.
The one posted by Alessandra is the final model sheet for the character and not a simple sketch.
It's taken from the POP series Villains Models Compilations (but she also appears in the single episodes model packs as well)
Octavia's Model Sheet design was added to POP in 1985.
As noted, it's labeled "Mattel Toy."

It seems that almost every character (or vehicles) in the POP series that were labeled "Mattel Toy" on the Model Sheets were characters that originated at Mattel as toys that Mattel specifically requested to incorporate in the cartoon.
You can see the same label on many other model sheets, like the Star Sister, Sea Harp, Netossa, almost all wave 2 characters, Colonel Blast (Rio Blast), Snout Spout, Tung Lashor, etc.
My theory is that Octavia was probably another toy in development at Mattel that was pitched to Filmation.
But again, this proves nothing about ownership and rights!

You won't find the same "Mattel Toy" label on the POP main cast model sheets (including the Evil Horde). Those appear to be developed by Filmation or by Filmation in conjunction with Mattel. My own belief is the creation of those particular characters is what probably is behind the complicated POP characters rights's situation we heard about many years ago when BCI was working with both ER and Mattel.

Let's talk about the toy design for Octavia.
I can't show you the art as it is in a private collection that I have been lucky enough to see.
But I can describe it to you.
It's important to keep in mind this is a MOTU figure design, not a POP one - it was developed to be included in the MOTU action figure line.
The original pencil drawing by Ted Mayer, "Octopus Woman" is dated June the 7th, 1984.
It's definitely a female horde member: she has the horde insignia on her chest, her legs and on the band on her left arm. She has a simple outfit, with a large belt and some sort of wide sleeves. She has 6 short tentacles in total (3 for each side), and black, short hairs.
While certain details doesn't match the final Filmation model sheet design, she looks like a preliminary version of Octavia.

The color rendering of her toy design has even more differences from the Filmation model.
It's the same pencil sketch, photocopied and pasted on a colored board, then rendered with what appears to be inks. She has purple skin, but the tentacles are green while her dress is blue. The date is 7-10-1984.
She's part of a large number of similar designs for produced and unproduced characters by Mattel.

My hopes are maybe we could get a toy version of the toy design done at Mattel on June 7th, 1984.
The coloring and details may have been different from the Filmation one, and she may have to have a different name. But, in spirit, she would still be "Octavia"

Going back to the subject of this thread, Scott's response about Octavia ownership was:
Although this sheet is labeled "Mattel toy" Octavia was a Filmation character and we do not have access to her at this time
You all know that I think she may have been originated at Mattel, but of course this doesn't mean they have rights to produce a MOTU figure of her.
Please do not misinterpret my historical theories on where designs were created to have anything to do with ownership and rights! They are not the same!!! Thanks.