Queen Seondeok

Lee Yo-won as Princess Deokman, later Queen Seondeok, 27th ruler of Silla, daughter of King Jinpyeong, twin sister of Princess Cheonmyeong.

Nam Ji-hyun as young Deokman

Go Hyun-jung as Lady Mishil, royal concubine of Jinheung, Jinji, and Jinpyeong. Sejong's wife, lover of Seolwon and mother of Bidam.

Uee as young Mishil

Park Ye-jin as Princess Cheonmyeong, daughter of King Jinpyeong, twin sister of Princess Deokman, mother of Kim Chunchu.

Shin Se-kyung as young Cheonmyeong

Kim Yoo-jung as 10-year-old Cheonmyeong

Uhm Tae-woong as Kim Yushin, general and Deokman's closest friend.

Lee Hyun-woo as young Kim Yushin

Kim Nam-gil as Bidam, son of Lady Mishil with King Jinji.

Park Ji-bin as young Bidam

Yoo Seung-ho as Kim Chunchu, later King Taejong Muyeol, son of Princess Cheonmyeong with Kim Yongsu.

Jung Yoon-seok as young Kim Chunchu

Lee Seung-hyo as Kim Alcheon, Deokman's and Yushin's friend.

Ho Hyo-hoon as young Kim Alcheon

Jung Ho-bin as Gukseon Munno, the 8th leader of Hwarang warriors and the Gukseon.

Jo Min-ki as King Jinpyeong, 26th king of Silla, father of Deokman and Cheonmyeong.

Baek Jong-min as young Jinpyeong

Kang San as child Jinpyeong

Yoon Yoo-sun as Queen Maya, King Jinpyeong's wife, mother of Deokman and Cheonmyeong.

Park Soo-jin as young Maya

Seo Young-hee as Sohwa, maidservant to Jinpyeong and Maya, foster mother of Deokman. Love interest of Chilsuk.

Im Ye-jin as Lady Manmyeong, King Jinpyeong's older sister, Kim Yushin's mother, Kim Seohyeon's wife.

Jung Sung-mo as Kim Seo-hyun, Manmyeong's husband, Kim Yushin's father.

Park Jung-chul as Kim Yong-su, King Jinji's eldest son, Princess Cheonmyeong's husband.

In Gyo-jin as Kim Yong-chun, King Jinji's 2nd son, a government minister, Princess Cheonmyeong's ally and confidante.

Shin Goo as Eulje, senior government minister, friend to King Jinpyeong.

Jung Woong-in as Misaeng, Mishil's younger brother, the 10th leader of Hwarang warriors.

Dokgo Young-jae as Sejong, Mishil's husband, the Prime Minister and 6th leader of Hwarang warriors.

Jeon No-min as Seolwon, Mishil's lover, the Minister of Defense and 7th leader of Hwarang warriors.

Kim Jung-hyun as Hajong, Mishil and Sejong's son, a government minister and the 11th leader of Hwarang warriors.

Baek Do-bin as Bojong, Mishil and Seolwon's son, a Hwarang commander.

Kwak Jung-wook as young Bojong

Song Ok-sook as Seori, chief mudang of Shilla, an old friend of Mishil and Misaeng.

Ahn Gil-kang as Chilsook, formerly a Hwarang, agent of Mishil.

Lee Moon-sik as Jookbang, a con artist who rips off the young Deokman and later joins Yu Shin's Hwarang.

Ryu Dam as Godo, a con artist who rips off the young Deokman and later joins Yu Shin's Hwarang.

Kang Sung-pil as Santak, Seokpum's, and later Bidam's, aide-de-camp.

Joo Sang-wook as Wolya, last prince of Gaya and the leader of the Bokya.

Jung Ho-keun as Seolji, Kayan commander loyal to Wolya.

Choi Won-young as General Gyebaek

Jun Young-bin as Gok Sa-heun

Jung Hyung-min as young Gok Sa-heun

Park Young-seo as Daepung

Lee Suk-min as young Daepung

Go Yoon-hoo as Hojae, the 14th leader of Hwarang warriors, later a council member of the hwabaek.

Hong Kyung-in as Seokpum, commander of a Hwarang loyal to Misil.

Noh Young-hak as young Seokpum

Kang Ji-hoo as Imjong, commander of a Hwarang loyal to Kim Yong-choon.

Kim Seok as young Imjong

Seo Dong-won as Deokchung

Lee Do-hyun as young Deokchung

Jang Hee-woong as Bakui

Seo Sang-won as young Bakui

Lee Sang-hyun as Piltan

Kim Tae-jin as young Piltan

Kim Dong-hee as Wangyoon

Choi Woo-sung as young Wangyoon

Ryu Sang-wook as Dae Nam-bo, the most prominent of Misaeng's sons, a Hwarang commander.

Kim Sang-bin as young Dae Nam-bo

Choi Sung-jo as Seonyeol

Oh Eun-suk as young Seonyeol

Kim Dong-soo as Hyeopseong

Moon Ji-yoon as Siyeol

Shin Tae-hoon as young Siyeol

Jung Hye-sun as Lady Man-ho, Jinpyeong and Manmyeong's mother.

Park Eun-bin as Boryang, Bojong's daughter, Kim Chunchu's wife.

Qri as Youngmo, Hajong's daughter, Kim Yushin's wife.

Seo Kang as Yangkil

Lee Soon-jae as King Jinheung, 24th King of Silla.

Im Ho as King Jinji, 25th King of Silla.

Park Jae-jung as Sadaham, Mishil's first love.