The folks at Nameberry have always been big fans of O Names -- starting with their first book, "Beyond Jennifer & Jason." A quarter-century later, choices like Leo and Marlo are officially stylish and other O names are gaining much-deserved attention. The only downside of the O names? There are more great choices for boys than for girls.

Here are Nameberry's picks for the best O names right now.

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  • Benno

    Benno is one of the most distinctive and undiscovered of the o-ending boys. Though it sounds like an Italian play on Ben, it's actually German, the name of an 11th century saint, patron of anglers, weavers and -- sufferin' succotash! -- alliteration. Two notable bearers: Benno Schmidt Sr., the venture capitalist who invented the term "venture capitalist," and Benno Schmidt, Jr., one-time president of Yale. <em>Pictured: Harkness Tower, Yale University.</em>

  • Clio

    As opposed to Cleo, which is short for the name of the Egyptian Queen of the Nile, Clio is the intriguing stand-alone name of the ancient Greek mythological muse of history and heroic poetry. The Clios are the annual awards given for innovation and excellence in the fields of advertising and design, adding further creative cred.

  • Hero

    Folks unfamiliar with Greek mythology might experience some gender confusion in response to this ancient girl's name, the heroine of a romantic legend, and the love interest of Claudio in Shakespeare's "Much Ado About Nothing." Hip British singer Myleene Klass chose it for her daughter.

  • Hugo

    This energetic Latin classic has gotten a lot of attention lately via the <a href="" target="_hplink">Martin Scorsese 3-D movie</a> and Hugo's "Harry Potter" appearance as the son of Ron and Hermione. <a href="" target="_hplink">Hugo</a> has been red hot in Europe recently -- a Top 10 name in Spain, France and Sweden -- and we expect it to keep rising in the U.S. as well.

  • Indigo

    The color name Blue and several of its shades (maybe not quite fifty) have been making their way onto birth certificates lately, and Indigo is one of the most striking, used for both girls and boys. Some other blue-hue possibilities: Azure, Sky, Navy, Teal, Cyan and Cerulean.

  • Juno

    Thanks largely to the indie movie hit of 2007, this ancient Roman goddess name is also a hit -- even if it hasn't entered the Social Security list just yet. One of the few o-ending options open to girls, <a href="" target="_hplink">Juno</a> is at once both strong and spunky and has nowhere to go but up.

  • Laszlo

    Suave and continental, Laszlo's image has morphed over the past few years from Hungarian aristo to cutting-edge kid. Many will associate it with noble and romantic cinema characters such as those in the films "Casablanca" and "The English Patient," and will also appreciate the double zip of its middle-z and o-ending.

  • Milo

    Milo is a 21st century shooting star. It entered the Top 1000 in 2001 and has risen every year since -- it's now at Number 361 -- as more and more parents, including several celebs, are attracted by its jaunty charm and multi-cultural roots. And featured roles in "Heroes" and "Alien" haven't hurt. <em>Pictured: Milo Ventimiglia and Olivia Munn.</em>

  • Nico

    Nico was one of the fastest-rising boy's names of the past year, climbing 95 places in 2011, seen as a fresher alternative to the starting-to-slip Nicholas/Nick. But the charm and energy of this nickname name is open to girls as well -- its best known bearer was the exotic German-born single-named female singer promoted by Andy Warhol. <em>Pictured: German Formula One driver Nico Rosberg.</em>

  • Orlando

    Beginning and ending <em>o</em>'s give this Shakespearean name a double dose of charisma. Famed also as the enigmatic protagonist of <a href="" target="_hplink">Virginia Woolf's celebrated novel</a>, it has been brought into the modern world by British actor Orlando Bloom, not to mention being the place-name locale of Disney World in Florida.

  • Otto

    This one-time Top 70 name was among the German classics that fell from favor following the two World Wars, but has returned to the popularity list just last year as the beginning of a possible revival. A palindrome with rare symmetry and balance and roundness, Otto could join Oliver, Oscar, Otis and other stylish o-names... though it might take a while.

  • Theo

    Many hip contemporary parents are skipping the formal Grandpa name of Theodore and going straight to the cool nickname Theo, which brought it back onto the pop list in 2010 after a hiatus of some 65 years. A Nameberry fave, its revival was impelled in part by the appealing character of Theo, the only son on The Cosby Show. Theo is currently mega-popular across Europe.