Tolong jelaskan mengenai Episode dari Star Trek: Discovery

Sonequa Martin-Green sebagai Michael Burnham: Seorang spesialis sains pada kapal USS Discovery yang dipromosikan menjadi kapten pada akhir musim ketiga. Burnham adalah seorang manusia yang dibesarkan di lingkungan dan budaya Vulcan oleh Sarek, menjadikannya sebagai adik tiri dari karakter Star Trek yang terkenal, Spock; alasan mengapa Spock tidak pernah menyebut Burnham di media Star Trek lain dijelaskan di musim kedua. Seorang protagonis non kapten dipilih untuk memberikan serial Discovery sudut pandang berbeda dari serial Star Trek sebelumnya, namun para penulis sudah tahu bahwa ia akan menjadi kapten. Walaupun dibesarkan dengan pemahaman logis dari Vulcan, Burnham memiliki sisi pemberontak yang ia tutupi walaupun sifat tersebut semakin terbuka sepanjang serial. Pencipta Discovery, Bryan Fuller memilih untuk memberikan karakter tersebut nama laki-laki seperti yang telah ia lakukan dengan protagonis perempuan pada tiga serial yang ia ciptakan sebelumnya.

Doug Jones sebagai Saru:  Mualim I pada USS Discovery yang menjadi kapten di musim ketiga. Saru adalah Kelpien pertama yang bergabung dengan Starfleet. Sebuah spesies baru yang diciptakan untuk Discovery, Kelpiens diburu sebagai mangsa di planet mereka dan berevolusi memiliki kemampuan untuk merasakan datangnya bahaya. Prosthetics are used to portray Saru, and initially took more than three hours to apply to Jones each day of filming. Jones based Saru's walk on that of a supermodel, out of necessity due to the boots he wore to portray the character's hooved feet. The producers compared Saru to the characters Spock and Data from previous Star Trek series.

Shazad Latif as Voq / Ash Tyler: Voq, an albino Klingon, undergoes extensive surgery to pose as the human Ash Tyler. He becomes chief of security for Discovery, and starts a relationship with Burnham. Voq's accent is Arabic-inspired, and Latif tried to maintain a "pharyngealness" to Tyler's American accent. To conceal from the audience that Voq and Tyler were played by the same actor, Latif was credited under the pseudonym "Javid Iqbal" for some of his appearances as Voq in the first season. For the second season, Latif felt he was playing a third character that melded Voq and Tyler in a similar way to Bruce Banner and the Hulk in Marvel Comics.

Anthony Rapp as Paul Stamets: Chief engineer aboard Discovery and a science officer specializing in astromycology (the study of fungi in space) who developed Discoverys experimental organic propulsion system (the "Spore Drive"). The character is inspired by a real-life mycologist of the same name. He is the first openly gay character in a Star Trek series. Rapp acknowledged that Hikaru Sulu is portrayed as gay in the film Star Trek Beyond (2016), calling that a "nice nod", but said the series would actually explore Stamets and his partner "in conversation, in our living quarters; you get to see our relationship over time, treated as any other relationship would be treated".

Mary Wiseman as Sylvia Tilly: An ensign aboard Discovery who works under Stamets and is initially Burnham's roommate. The character was intended to represent people at the bottom of the Starfleet hierarchy, and season one co-showrunner Aaron Harberts said she was the "soul" of the series. She is temporarily promoted to first officer by Saru in the third season, and chooses to leave the ship in the fourth to become a teacher at Starfleet Academy.

Jason Isaacs as Gabriel Lorca (musim 1): Captain of the Discovery in the first season who was described as a "brilliant military tactician". Isaacs said the character was "probably more fucked up than any of" the previously seen Star Trek captains. He plays the character with a slight southern U.S. accent, and initially ad-libbed the catchphrase "git'r done" before the writers pointed out that it was already widely used and trademarked by Larry the Cable Guy.

Wilson Cruz as Hugh Culber: Medical officer aboard Discovery and Stamets' husband. Cruz said portraying the first openly gay couple in Star Trek was "a long time coming" and praised the subtle way that the series explored their relationship. The character is killed in the first season, but returns from the dead in the second and subsequently goes through post-traumatic growth. He becomes an advocate for the mental health of the crew in the third season.

Anson Mount as Christopher Pike (musim 2): Captain of the Enterprise who takes temporary command of the Discovery in the second season. Mount described Pike as "very by-the-book" and a good person, while executive producers Heather Kadin and Alex Kurtzman said he was the opposite of Lorca with "enough confidence and authority to apologize when he is wrong". Mount did not try to imitate original Pike actor Jeffrey Hunter's performance from The Original Series.

David Ajala as Cleveland "Book" Booker (musim 3-): The first person that Burnham meets in the 32nd century, Book helps introduce the third season's new future setting. He is a "courier", an independent trader, and becomes a love interest for Burnham that the writers hoped would bring out new sides to her character in contrast to her tumultuous relationship with Ash Tyler in the previous seasons. The producers took inspiration from Star Wars character Han Solo for Book, especially for his costumes. The character has a pet cat named Grudge who is portrayed by two Maine Coons, Leeu and Durban. They are  long and weigh .

Rachael Ancheril as Nhan (musim 2-3):  A former Enterprise crewmember who becomes chief of security for Discovery in the second season. Nhan leaves the ship in the third season during the 32nd century.

Blu del Barrio as Adira Tal (musim 3-): A human bonded with a Trill symbiont. Adira is the first non-binary character to feature in a Star Trek series, and the writers worked with del Barrio and LGBTQ media monitoring organization GLAAD when developing the character due to there being no non-binary writers working on the series. Adira and their transgender boyfriend Gray (portrayed by Ian Alexander) form a "family unit" with Stamets and Culber in the third and fourth seasons.

Tig Notaro as Jett Reno (musim 2-): An engineer who joins Discovery in the second season. Notaro was a long-time friend of Kurtzman's when he asked her to join the series as comedic relief. The character was originally called Denise Reno, but she was able to change the name and chose "Jett" for singer Joan Jett. To accommodate Notaro's busy schedule of stand-up comedy and other projects, she filmed her scenes from different episodes, at the same time.