Captain Benjamin Sisko
In Star Trek: Deep Space Nine, which aired from 1993 to 1999, Captain Benjamin Sisko (played by Avery Brooks) is the central character and commander of the Deep Space Nine space station, which borders a wormhole that leads to another section of the Milky Way galaxy.
An empire of hostile aliens called “The Dominion” lives on the other side of the wormhole. As “the Emissary of the Prophets,” Captain Sisko is a divine figure to the White Bajoran people, routinely interacts with the Bajoran gods and saves humanity and the entire galaxy from the evil shapeshifters and their drug-addicted reptilian soldiers when they launch an invasion of the Alpha Quadrant.
Worf
Worf is a main character in Star Trek: The Next Generation and in seasons four through seven of Star Trek: Deep Space Nine. He also appears in the films based on The Next Generation. Worf is the first Klingon main character to appear in Star Trek, and has appeared in more Star Trek franchise episodes than any other character.
Worf (played by Michael Dorn) joins the USS Enterprise-D as lieutenant junior grade, as relief con and tactical officer, and is later made security chief. He is the only Klingon in Starfleet and grows accustomed to the strange reactions this brings.
Worf values honor and loyalty above all else. He is often torn between his human upbringing and his Klingon culture, as evidenced by the traditional Klingon baldrics he wears over his Starfleet uniform.
Another would be Paul Winfield in the episode "Memory Alpha." He wasn't a regular character/cast member, but it was memorable. He played Darkmok, a Tamarian. The Tamarians spoke only in metaphor. To let Picard know that he was willing to discuss, he would say something like, "Darmok with arms wide open." Picard had to learn his language to communicate. One of the most ingenious and best episodes of ST: TNG and the late Paul Winfield was brilliant in the guest starring role.
I would second adding the great actor William Marshall as the genius "Richard Daystrom" from the original series whose Daystrom Institute is mentioned often in later episodes of Star Trek. And you can't exclude Paul Winfield from one of the highest rated episodes of TNG, "Memory Alpha. This story about the importance of communication among people is on every list of top 10 episodes.
Yeah seriously this list is waaaay too short and I can't fathom how they didn't include Whoopi Goldberg.
…but what about the amazing Tony Todd! Not only as "Kurn" but his INCREDIBLE performance as Jake Sisko in "The Visitor!"
What? Clarence Williams III as the colds Jem Hadar ever Omet'iklan.
Agree on all counts.