Lelouch vi Britannia from Code Geass is a borderline example. Apparently the idea of him wearing a mask came from executives who said something along the lines of "It just wouldn't be a Sunrise show without a mask".
Sayla Mass, Char's younger sister, has expies of her own in Cecily Fairchild, Relena Darlian, and CagalliYulaAthha (who also shares traits with Relena). The common traits shared among these characters are that they were exiled princesses who adopted a different alias, has a strong relationship with the lead character, and she has a relative who's (usually) the lead character's main rival.
A surprising combination of the rebellious princess archetype (and a mishmash of some of Mobile Suit Gundam SEED's female characters) appears in Angelise Ikaruga Misurugi, the titular heroine from Cross Ange. Carrying the looks and piloting skills of Stella Loussier, the tomboyish disposition and attitude of Cagalli, and a singing voice to rival Lacus, Ange also pilots Ragnamail Villkiss, which itself is an expy of the two most prominent Gundams from SEED Destiny.
Char's boss, Gihren Zabi, has also had his fair share of expies. There's Fonse Kagatie from Victory, Siedel Rasso from Gundam X, Patrick Zala from Gundam SEED, Rustal Elion from "Iron-Blooded Orphans", and Delling Rembran from "The Witch from Mercury", all of whom share Gihren's status as amoral military dictators who preach a Master Race philosophy and have a love of superweapons. Patrick even duplicates Gihren's infamous "Sieg Zeon!" speech in his rant about "Who exploits the Coordinators"? Gihren's son and/or clone, Glemmy Toto has his own expy in SEED's Muruta Azrael, who shares his looks, childish demeanour, creepy interactions with women, willingness to use children as weapons, and total lack of scruples.
Mecha Expies are also par for the course in Gundam. Wing's Shenlong Gundam is an Expy of G's Dragon Gundam (both are Chinese dragon themed mecha with extendable arms and carry a polearm), X's Leopard is an Expy of Wing's Heavyarms (loaded with lots of guns and the main weapon is a largeGatling gun), and Deathscythe and Deathscythe Hell resemble Master Asia's Kowloon and Master Gundams respectively (with retractable metal "cloaks" that make them look bulkier than they really are).
The grunt suits are almost always based on either the Zaku since they have the green color scheme (like the Dark Army Mobile Suit or the Graze), Cyber Cyclops head design (like the Jenice and the GINN), and plain tank-like build (like the Leo ans the Tieren) of Zeon's original mass-produced mobile suit.
In the CE timeline, here are their mecha expies:
Strike = RX-78-2 Gundam
Freedom = Gundam Formula 91 + Gundam Double X
The Impulse is based on the RX-78-2 Gundam, but plays a role similar to the Gundam Mk. II in Destiny. Similarly, Destiny played a role similar to the MSZ-006 Zeta Gundam.
Heero Yuy, the archetypical stoic lead Gundam pilot, has his expies in Setsuna F. Seiei, Mikazuki Augus, and to a lesser extent, Sven Cal Bayan and Hiroto Kuga.
Gundam Wing: Endless Waltz has Mariemaia Khushrenada, who is based on MinevaLaoZabi, being the daughter of a deceased major villain who's used as a figurehead by the true leader of the new villain faction.
Sting Oakley and Auel Neider are Expies of two characters from Gundam SEED, with Sting playing Clotho Bauer to Auel'sShani Andras. The Boosted Men and the Extended as a whole are a collective expy of UC's Cyber-Newtypes, each being Muggles who were upgraded with surgery and drugs to duplicate the the powers of Coordinators and Newtypes, respectively.
Garrod Ran is something of an expy of Judau Ashita, since both were war orphans who couldn't help but get caught up in the events of the world around them and both grew into real badass (or in the case of Garrod Badass Normal) pilots, and even though they both had reason to neither one of them succumbed to their Heroic BSoD for very long. Both also specialize in stealing mobile suits at the start of their respective series.
Both Gundam Wing's Heero Yuy (the original one, the namesake of the Gundam pilot) and King Peacecraft, as well as Gundam SEED's George Glenn, were based on Zeon Zum Deikun, as charismatic visionary leaders whose ideologies play major roles in their respective series and whose murders are pivotal moments that greatly escalate conflict in each timeline. Uzumi Nara Athha is based on King Peacecraft. Uzumi is the only one of these to not be a Posthumous Characteruntil a Heroic Sacrifice takes care of that problem.
As for the rest of the Gundam SEED characters:
Murrue Ramius = a gender-flipped Bright Noa, with Archangel being White Base.
Murrue has her own expy in Gundam 00's Sumeragi Lee Noriega; her Commander Contrarian, Natarle Badgiruel, lives on as Kati Manniquin.
Mu La Flaga = Sleggar Law with some of Char's Quattro persona thrown into the mix.
Andrew Waltfeld = Ramba Ral, with Aisha as his Crowley Hamon.
Nicol Amalfi = Quatre Raberba Winner; they're both kind-hearted pilots with a love for music.
Admiral Lewis Halberton = General Revil
The DOM Trooper pilots (Hilda, Mars, and Herbert) = the Black Tri-Stars; they even have the Tri-Stars' signature Jet Stream Attack. The only difference is that one is gender-flipped and this time they're Elite Mooks in the heroes' army.
And now Gundam AGE has Yurin L'Ciel as an expy of Tiffa Addil from Gundam X, being both loli Mysterious Waif characters that help the main hero with their clairvoyance powers. Unlike Tiffa, however, Yurin ends up as the Phlebotinum Girl of the series and is heartlessly killed by Desil Galette.
Emily Amonde, Lunamaria Hawke, and Fa Yuriy are expies of Frau Bow in this following concept: She is a semi-major character who despite having no direct conflict with or impact toward the main story, initially has a close relationship with the protagonist, and join the boy's fleet to "look after" with him. She likes him, but he doesn't notice her because he loves somebody else. In /he cases of the above three, however, they do end up winning their crush's heart (Emily with Flit, Luna with Shinn, Fa with Kamille). She also tends to suffers from the Stay in the Kitchen issue (or in Luna's case, The Worf Effect).
Macross director Noburo Ishiguro stated that Roy Focker was based on Sleggar Law.
Gundam SEED's Kira Yamato, male Shrinking Violet and general Nice Guy who has a penchant for surviving things exploding right in his face, gets an expy in Tusk from Cross Ange, right down to the brown hair and purple eyes. While not a Martial Pacifist and being far more willing to kill when necessary, Tusk shares Kira's optimism and has a protection complex towards Ange, his Love Interest. Also like Kira, he gets to share his first time on-screen with his beloved; the difference being that Kira's girlfriend, Flay Allster, was manipulating him with sex (and ultimately, that relationship ended horribly). In contrast, the love scene Tusk shares with Ange is completely genuine and heartfelt.
Loran Cehack, the protagonist of ∀ Gundam, gains one in the Ad Stella timeline with Kiyu Lavot.
