Shtrughna: Younger son of Dashrath and Sumitra isn't mentioned much but his character in Uttar Kand shines where he defeated Lavanasura, King of Madhupuri (Mathura) and son of Madhu and Kumbhinasi. He established the region of Shurasenas. Shtrughna was deeply devoted to both Shri Ram and Bharat and he was biological brother of Laxman. He was the one who got to know first that Mata Sita had given birth to twins when he halted at Maharishi's Ashram. So , he knew the truth much before than anyone else but he didn't interfere as it was decision of Shri Ram and such a revelation was deeply personal to the couple so he didn't meddle.
Tara- Wife of Vali and later Sugriva is a very intelligent woman in Valmiki Ramayana and Vali says to Sugriva to always listen to sane advise of Tara. Tara is not a flawless woman but she is also not a villain. She drank wine, married two brothers but her intellect and administrative wisdom is praised in the epic. Her true personality is rarely shown in television serials. Tara deeply grieved loss of Vali.
Urmila- She is not mentioned in the epic much but later retellings extensively praises her character and shows her as a self sacrificing woman who let her husband leave and suffered separation for fourteen years. It would have been amazing if the original epic focussed on her POV. The POVs of Mandavi and Shrutkirti are also not given. It's not mentioned whether Mandavi was in Nandigram or not with Bharat. Urmila's sacrifices are highly glorified in later retellings and being daughter of Rajrishi Janaka, it's expected of her.
Champika- The daughter of Maharaja Bhurikirti and first wife of Kusha is not mentioned in Valmiki Ramayana but in Ananda Ramayana. The woman deserves notice because she was first wife of Kusha and she chose him in Swayamvar. She stayed with him as his dutiful wife in Kushavati and later in Ayodhya. She birthed nine daughters and even after prophecy that she would give birth to daughters and no sons, Kusha remained with her as her support and strength. The respect she had in his home was immense. His second marriage to Kumudvati was out of love and alliance and not because Champika only had daughters. Even after his marriage with Kumudvati, Kusha and Champika’s relationship remained harmonious. It shows how much queens used to sacrifice for their kings and stability of Kingdom. She gave him love and support in his initial life when he was suffering from trauma of losing his mother. Champika's glorious character is like Kaushalya who despite her husband loving another wife remained extremely devoted and supportive. Her sacrifices gave stability to Kusha’s initial reign.
Kumudvati- Again, the Naga Princess is not mentioned in Valmiki Ramayana but in two sources, Ananda Ramayana and Raghuvansh written by Kalidas. She was sister of Naga King Kumud. She mistakenly took Kusha’s golden arm- bracelet gifted by his father and kusha who was sporting in Sarayu with Champika and his other Junior wives and he got angry. He was about to attack Nagas when Kumud came and apologized. The sincere apology, Kumud’s royal demenor and wise nature made them friends. He offered his sister's hand in marriage to Kusha and due to love at first sight and to make a strong alliance, he accepted Kumudvati. She is praised in both sources for saving the Raghkula’s main line by providing sons , specially their first son Atithi who was very handsome, meritorious and extremely wise. Kumudvati and Kusha's surpassed the image of alliance marriage and developed very genuine attachment withel each other. She followed him in death despite being new Rajmata. Kusha built Nageshwarnath Temple near Sarayu river because Kumudvati was Lord Shiva’s devotee and due to remains of this temple, Raja Vikramaditya could find the original location of Ayodhya.
Vanaras- Vanaras as a group are pillar of Shri Ram's victory in every Ramayana. Sushena, Nala, Nila, Hanuman, Sugriva, Angad etc. Without their support, Ram would have difficulty in recovering Mata Sita. Each Vanara (including Jambavant) gave their best to support Shri Ram in rescuing Mata Sita.