Is Cassandra actually Mother Gothel? No.
And here’s why.
I’ve seen several people speculating recently that Cassandra may be Gothel in disguise. Personally, I feel that this theory is… beyond ridiculous. There are several extremely big reasons why I feel this way. I’ll start with the first thing that people have been using as their evidence.
Yes, perhaps their coloration is similar. But their eye shape is completely different. Gothel’s eyes are also characterized by her heavy lids, which Cassandra doesn’t have. Their noses aren’t the same shape - Gothel’s is downturned while Cassandra’s is upturned. Their lips aren’t the same shape, either. And while the characters in Tangled the Series are stylized, their shapes are blocked accurately to the character designs. Also, Cassandra’s hair isn’t nearly curly enough to be Gothel’s hair. When curly hair is cut, it gets curlier, not straighter, and Cassandra’s hair is definitely not as curly as Gothel’s.
Mother Gothel is voiced by Donna Murphy. Cassandra is voiced by Eden Espinosa. Considering how many of the original cast they got back from the movie - Mandy Moore, Zachary Levi, M.C. Gainey, Jeffery Tambour, Paul F. Tompkins - I can’t fathom them getting someone who doesn’t sound remotely like Donna Murphy to play someone who is supposed to be Gothel, even in disguise.
3) Cassandra tries to cut Rapunzel’s hair:
Gothel would never try to cut Rapunzel’s hair! Even if she found a new way to stay young forever, she is a woman of plans, and leaving Rapunzel’s hair long would be a contingency plan in case whatever was keeping her alive somehow failed (like Rapunzel’s hair failed before). Not to mention, it’s what Rapunzel wants. If this was Gothel, she’d be manipulating her into trying to keep it, not doing something that makes Rapunzel more comfortable for Rapunzel’s own sake.
4) Gothel is dead:
And boy, is she ever dead! She’s so dead that she is dust, scattered on the ground. “But what if someone found a way to revive her?” I hear you cry.
Let’s examine Gothel’s character for a moment. She was a woman who was hiding a secret for hundreds of years. A really big secret. That is not conducive to making friends who are close enough that they’d come looking for you if you went missing. Also, even if she did have someone that close, how would they find her… dust? The tower was part of the secret, and we don’t know how long she was living there before she brought Rapunzel there, so for a minimum of eighteen years, she’s been managing to keep the tower hidden. Eugene didn’t know it was there. The guards didn’t know it was there. Whether she lived there or not prior to kidnapping Rapunzel, it was still clearly extremely well hidden, and in an attempt to keep Rapunzel’s hair to herself, she wouldn’t be going around telling anyone about its location.
So, in conclusion, they don’t look enough alike, they don’t sound alike at all, Cassandra attempts to cut Rapunzel’s hair (something Gothel would never do) and the biggest factor, Gothel is dead. Cassandra is not Gothel in disguise.