- O' Neill, Kimberly: Certified Tester - Foundation Level
- O'Brien, Katlyn J: Certified Tester - Foundation Level
- O'connor, Marian: Certified Tester - Foundation Level
- O'Gorman, Kieron James: Certified Tester - Foundation Level
- O'Hanley, Lisa Denise: Certified Tester - Foundation Level
- O'Neill, Troy James: Certified Tester - Foundation Level
- O'Regan, Katherine: Certified Tester - Foundation Level
- O'Reilly, Steven: Certified Tester - Foundation Level
- Oakley, Helen: Certified Tester - Foundation Level
- Obad, Dennis: Certified Tester - Foundation Level
- Oberoi, Taranjeet: Certified Tester - Foundation Level
- Obiki, Ndudi: Certified Tester - Foundation Level
- Obradovic, Dragoslav: Certified Tester - Foundation Level
- Oburi, Naveen : Certified Tester - Foundation Level
- Ochneva, Anna: Certified Tester - Foundation Level
- Odeniyi, Austin: Certified Tester - Foundation Level
- Odetoyinbo, Adetomiwa: Certified Tester - Agile Tester
- Odetoyinbo, Adetomiwa: Certified Tester - Foundation Level
- Ogadu, Ehimen: Certified Tester - Acceptance Testing
- Ogboghodo, Dennis: Certified Tester - Foundation Level
- Ogden, Tracy Lea: Certified Tester - Foundation Level
- Ogunwale, Bukola: Certified Tester - Foundation Level
- Oh, Kwang Tae (Ted): Certified Tester - Foundation Level
- Oka, Leo: Certified Tester - Foundation Level
- Okaekwu, Adesua: Certified Tester - Foundation Level
- Okaekwu, Onyeka Malcolm: Certified Tester - Foundation Level
- Olabode, Temitope: Certified Tester - Agile Tester
- Olabode, Temitope: Certified Tester - Foundation Level
- Oladele, Kunle Oladipo: Certified Tester - Foundation Level
- Oladimeji, Christopher A D: Certified Tester - Foundation Level
- Olantunde Olaleye, Anthony: Certified Tester - Foundation Level
- Olisekwe, Chioma: Certified Tester - Foundation Level
- Oliver, Sylvie: Certified Tester - Foundation Level
- Olivieri, Celina M.: Certified Tester - Foundation Level
- Olorunsola, Lola: Certified Tester - Foundation Level
- Olugbenjo, Debbie: Certified Tester - Foundation Level
- Olusile, Ademola : Certified Tester - Foundation Level
- Oluyomi, Emmanuel: Certified Tester - Foundation Level
- Omer, Sardar Usman: Certified Tester - Foundation Level
- Omid, Mohammad Elham: Certified Tester - Foundation Level
- Omodara, Bamidele: Certified Tester - Foundation Level
- Omotosho, Balqees O.: Certified Tester - Foundation Level
- Ong, Jonathan: Certified Tester - Foundation Level
- Ong, Marilyn: Certified Tester - Foundation Level
- Ong, Patricia: Certified Tester - Foundation Level
- Onyeogu, Frank Azubuike: Certified Tester - Foundation Level
- Onyeogu, Frank Azubuike: Advanced Level - Test Manager
- Onyshchuk, Roman: Certified Tester - Foundation Level
- Or, Yee Wa: Certified Tester - Foundation Level
- Orajiaka, Blessing: Certified Tester - Foundation Level
- Oravampuram Mana, Jisha: Certified Tester - Foundation Level
- Organ, Daniel: Certified Tester - Foundation Level
- Orozco, Luis: Certified Tester - Foundation Level
- Orozco, Luis: Advanced Level - Test Manager
- Orti, Carol V.: Certified Tester - Foundation Level
- Ortiz, Miguel Angel: Certified Tester - Foundation Level
- Ortiz Ayma, Giovana Jenny: Certified Tester - Foundation Level
- Ositashvili, Caterina: Certified Tester - Foundation Level
- Osman, Bulban: Certified Tester - Foundation Level
- Osman, Mohamed: Certified Tester - Foundation Level
- Osmond, Paul: Certified Tester - Foundation Level
- Ostrobrod, Leonid: Certified Tester - Foundation Level
- Ostrowski, Teresa: Certified Tester - Foundation Level
- Otman, Saufi: Certified Tester - Foundation Level
- Ottati, Ignacio: Certified Tester - Foundation Level
- Ou, Hai Ying: Certified Tester - Foundation Level
- Ouafi, Haykel: Certified Tester - Foundation Level
- OUDDAI, Sarra: Certified Tester - Foundation Level
- Ouimet, Elise: Certified Tester - Foundation Level
- Ovens, Barry: Certified Tester - Foundation Level
- Oxenham, Michael: Certified Tester - Foundation Level
- Oxenholm, Meredith: Certified Tester - Foundation Level
- Oyetti, Jonathan: Certified Tester - Foundation Level
- Ozogbuda, Japhet: Certified Tester - Foundation Level