| Marginal Variegation | Plant Size | Leaf Color | Var Color | Origin | Season | Source | Registered |
| 'Oberland Advanced Technology' | Large | Light-Green | White | Unknown | July into August | Rank, Stefan | .2013 |
| 'Oberland Thin Line' | Medium | Blue/Green | Yellow | Sport | July into August | Rank, Stefan | --NR-- |
| 'Obsession' | Medium | Med-Green | Greenish White | Sport | August | Avent, Tony | .1998 |
| 'Occupy Wall Street' | Small | Blue/Green | White | Unknown | July into August | Freeman, Franc | .2012 |
| 'Ocean Isle' | Large | Blue/Green | Yellow | Sport | July | Chopko, Dave | .2006 |
| 'Ocean Isle Gold' | Large | Med-Green | Yellow | Unknown | June into July | Chopko, Dave | --NR-- |
| 'October Fest' | Medium | Blue/Green | Yellow | TC Sport | June into July | Van den Top, Jan | --NR-- |
| 'Odo' | Small | Light-Green | Dark Green | Unknown | - | Dupre, Dirk | --NR-- |
| 'Og, Son of Fire' | Miniature | Med-Green | White | Hybrid | - | Beilstein, Doug & Malloy, Alex | --NR-- |
| 'Ogon Albomarginata' | Small | Yellow | White | Sport | - | Unknown | --NR-- |
| 'Ogon Hime' (Landis) | - | Med-Green | Yellow | Sport | - | Landis, Henry | --NR-- |
| 'Oh Audrey' | Medium | Light-Green | White | Sport | June into July | Silvers, Bill | .2013 |
| 'Oh by Gosh' | Large | Med-Green | Yellow | Sport | July | Rudolph, Thelma & Ruh, Peter | .2000 |
| 'Oh Charlie' | Large | Med-Green | Yellow | TC Sport | July | Ziarek, Ken | --NR-- |
| 'Ohh! Amber' | Small | Dark-Green | White | Hybrid | July into August | Schultz, Ed | .2021 |
| 'Ohh! Richland Reward' | Medium | Yellow | White | TC Sport | July into August | Schulz, Ed | --NR-- |
| 'Ohh! Tut's Treasure' | Medium | Dark-Green | Yellow | Sport | June into July | Schulz, Ed | --NR-- |
| 'Okan' | Large | Med-Green | Yellow | Hybrid | - | Unknown | --NR-- |
| 'Okaydokey' | Medium | Yellow | Dark Green | Sport | July into August | Walters Gardens & Walek, Kevin | .2009 |
| 'Okefenokee' | Medium | Med-Green | Yellow | Sport | July into August | Benedict, Dr Ralph (Herb) & Walek, Kevin | .2009 |
| 'Old Glory' | Large | Yellow | Blue-Green | Sport | June into July | Hansen, Hans & Shady Oaks Nursery | .1999 |
| 'Old Gold Edge' | Medium | Dark-Green | Yellow | Unknown | - | Tompkins, Cynthia | --NR-- |
| 'Olive Bailey Langdon' | Giant | Blue/Green | Yellow | Sport | June | O'Harra, Russ & Russ O'Harra Hosta Society | .1999 |
| 'Olive Oyl' | Large | Med-Green | Yellow | Unknown | - | Carlson, Monty & Carlson, Julie | --NR-- |
| 'Oliver' | Small | Med-Green | White | Unknown | - | O'Harra, Russ | --NR-- |
| 'Olympic Edger' | Small | Med-Green | Yellow | Sport | June into July | Naylor Creek Nursery | .1999 |
| 'Olympic Glacier' | Medium | Dark-Green | Yellow | Sport | July into August | Naylor Creek Nursery | .2005 |
| 'Olympic Twilight' | Medium | Blue/Green | Yellow | Sport | July into August | Naylor Creek Nursery | --NR-- |
| 'Omega' | Large | Med-Green | Yellow | Unknown | - | Unknown | --NR-- |
| 'On Golden Pond' | Giant | Dark-Green | Yellow | Hybrid | July | Elslager, Ed | .2005 |
| 'On the Border' | Medium | Med-Green | White | Hybrid | August | Beilstein, Doug | .2007 |
| 'On the Edge' | Medium | Light-Green | Blue-Green | Sport | June | Scolnik, Patricia | --NR-- |
| 'Once upon a Time' | Medium | Med-Green | White | Hybrid | August | Wilkins, Dr Jim & Wilkins, Sandy | .2002 |
| 'One Fine Day' | Medium | Med-Green | Yellow | Hybrid | June into July | Ward, Dr Dick & Ward, Jane | .2012 |
| 'One Iota' | Small | Blue/Green | White | TC Sport | July | Anderson, Jim | --NR-- |
| 'One Last Dance' | Large | Dark-Green | Yellow | TC Sport | July | Hansen, Hans & Walters Gardens | .2020 |
| 'Only You' | Medium | Med-Green | White | Hybrid | - | Ward, Dr Dick & Ward, Jane | .2012 |
| 'Opipara' | Medium | Med-Green | Yellow | Unknown | July into August | Maekawa, Dr Fumio & The American Hosta Society | .2002 |
| 'Opipara Koriyama' | Medium | Med-Green | White | Unknown | August | Unknown | --NR-- |
| 'Oplosa' | Medium | Blue/Green | Creamy White | Unknown | - | Unknown | --NR-- |
| 'Orange Crush' | Medium | Med-Green | Creamy White | Hybrid | July | Elslager, Ed | .2000 |
| 'Orphan Annie' | Miniature | Med-Green | White | Unknown | July | Unknown | --NR-- |
| 'Oshima Silk' | Medium | Med-Green | White | Hybrid | August to September | Shimizu, Toshirou & Zilis, Mark | .2009 |
| 'Osiris Le Petit Roi' | Miniature | Med-Green | Yellow | Unknown | | Fafard, Serge | --NR-- |
| 'Osiris Marie Robillard' | Large | Blue/Green | Light Green | Unknown | - | Fafard, Serge | --NR-- |
| 'Osiris Mignonne' | Small | Light-Green | White | Unknown | - | Fafard, Serge | --NR-- |
| 'Osiris Mirage' | Small | Light-Green | White | Unknown | - | Fafard, Serge | --NR-- |
| 'Osiris Pacha' | Medium | Med-Green | Yellow | Unknown | - | Fafard, Serge | --NR-- |
| 'Osiris Soleil Levant' | Large | Med-Green | Yellow | Unknown | - | Fafard, Serge | --NR-- |
| 'Osiris Trouvaille' | Large | Blue/Green | Yellow | Unknown | - | Fafard, Serge | --NR-- |
| 'Otara's Angel' | Large | Dark-Green | Yellow | Sport | June into July | Johns, Eddie | --NR-- |
| 'Otara's Sunrise' | Large | Med-Green | White | Unknown | - | Johns, Eddie | --NR-- |
| 'Otome Gokoro' | - | Med-Green | White | Duplicate | - | Duplicate Name | --NR-- |
| 'Ototo San' | Miniature | Dark-Green | White | Unknown | August to September | Ruh, Peter | .1990 .2018 |
| 'Our Child' | Medium | Dark-Green | Yellow | Unknown | - | Unknown | --NR-- |
| 'Outer Space' | Small | Light-Green | White | Sport | July | Malloy, Alex | .2003 |
| 'Outside' | Small | Light-Green | Yellow | Unknown | - | Goodwin, Randy | --NR-- |
| 'Over the Moon' | Medium | Med-Green | White | Hybrid | June into July | Ward, Dr Dick & Ward, Jane | .2010 |
| 'Oxymoron' | Small | Blue/Green | White | Sport | July | Harle, Dennis | --NR-- |
| 'Oz' | Large | Med-Green | White | Sport | - | Malloy, Alex | --NR-- |
| 'Oze' | Miniature | Med-Green | Yellow | Unknown | August | Unknown | --NR-- |
|