Twitter has a couple big names in the spotlight:
But there are a number of other key players who are responsible for creating and growing Twitter, and running it now.
Evan Williams, Twitter's largest individual shareholder with 10 percent of the company post-IPO, was CEO until he was ousted by the board in 2010. He was replaced by Costolo, who was brought in as COO the prior year.
Williams co-founded Obvious Corp., an incubator for Web media companies and an investment firm of sorts, along with Twitter's former chief creative director, Biz Stone, who left Twitter at the same time as Williams.
(Read more: Twitter's mysterious outside shareholder )
Obvious' main project is a publishing platform called Medium, which launched last year. Medium offers an alternative-almost an antidote to Twitter's 140 character limitations. It's designed for easily sharing and reading longer-form content-magazine-style articles. It helps writers find an audience and helps readers find relevant content, enabling them to comment and share with friends.
Stone and Williams' Obvious also backs a very different kind of start-up outside the media space-Beyond Meat. Its vegan meat alternatives like Veggie Chicken Strips are considered pretty close to the real thing, and are available in grocery stores including Whole Foods.
Stone recently announced a solo start-up venture, called Jelly. It's in stealth mode, and he hasn't revealed anything about it other than it is hiring and it'll be focused on mobile.
The co-founder furthest from Twitter's nest is Noah Glass. He left soon after Twitter launched, following a falling-out with his co-founders. Glass' Twitter profile says "I started this," but he doesn't Tweet often.
His LinkedIn profile is also limited-saying he co-founded Odeo (the start-up where he, Williams, Stone and Dorsey hatched the idea for Twitter).
All the founders declined requests for comment.
Facebook's IPO put its COO Sheryl Sandberg and CFO David Ebersman in the spotlight. Here are their counterparts at Twitter: CEO Costolo's right hand is COO Ali Rowghani, who joined Twitter in 2010 as CFO after holding that same position at Disney's Pixar Animation Studios, where he worked for nine years. He switched to the COO role when Costolo brought in CFO Mike Gupta.
Gupta joined Twitter a year ago from Zynga where he was treasurer for just one year. Before his short stint at Zynga he was a senior executive at Yahoo, focusing on search at online partnership deals.
(Read more: Twitter gets a warning from tech veteran )
In a growing public role, explaining the company's ad strategy, is Chief Revenue Officer Adam Bain, who Costolo hired away from News Corp. back in 2010, when he was still in the COO role. Bain oversees all of Twitter's ad products-constantly looking to improve targeting and measurement-and investigating future ways to make money.
Bain draws $6.7 million in total compensation, the third-highest compensation at Twitter after CEO Dick Costolo, with $11.5 million in 2012 cash and stock.
Christopher Fry is the senior vice president of engineering, with $10.3 million in total compensation. His role is anything but public, but it's certainly crucial to avoiding "Fail Whales"-he oversees Twitter's engineering department.
Another major player in Twitter's IPO and the most senior woman at the company is general counsel Vijaya Gadde. She's guiding the legal and regulatory side of the IPO process and plays a key role in helping Twitter defend its users' right to free speech around the world.
She previously worked as associate general counsel at Juniper Networks, and as an attorney before that.
Twitter executives declined to comment for this story, saying the company is in a quiet period ahead of its IPO.
-By CNBC's Julia Boorstin. Follow her on Twitter: @JBoorstin .
image: © Howard Lake