| Name(asc) | City | Country / Territory | Chartered? | Membership grade | Profile link |
|---|---|---|---|---|---|
| Eur Ing Arthur OWEN | Caillac | France | Fellow | View | |
| Miss Sheila OSMANOVIC | London | United Kingdom | Member | View | |
| Miss Sheila OSMANOVIC | London | United Kingdom | Member | View | |
| Mr Mohamed Osman Abdalla | Leeds | United Kingdom | Member | View | |
| Mr Abdi Osman | Manchester | United Kingdom | CL (Translator) | Member | View |
| Mr Abdi Osman | Manchester | United Kingdom | CL (Translator) | Member | View |
| Mrs Heike OSBORNE | Bruchsal | Germany | Member | View | |
| Dr David ORTON | Blandford Forum | United Kingdom | Fellow | View | |
| Dr David ORTON | Blandford Forum | United Kingdom | Fellow | View | |
| Mr Miguel ORTIZ | London | United Kingdom | Member | View | |
| Ms Laura ORSINI | West Dulwich | United Kingdom | CL (Translator) | Member | View |
| Mrs Gwennola ORIO-GLAUNEC | London | United Kingdom | Member | View | |
| Miss Jessica Oppedisano | London | United Kingdom | CL (Translator) | Member | View |
| Mr Colin OPIE | Torquay | United Kingdom | Member | View | |
| Ms Yumiko OMURA | London | United Kingdom | Member | View | |
| Mr Gokhan Omur | London | United Kingdom | Member | View | |
| Mr Richard OLIVER | East Harling | United Kingdom | Member | View | |
| Mr Richard OLIVER | East Harling | United Kingdom | Member | View | |
| Mrs Mariza Gabriela Oliveira Sousa Cardoso | Birmingham | United Kingdom | Associate | View | |
| Mrs Mariza Gabriela Oliveira Sousa Cardoso | Birmingham | United Kingdom | Associate | View | |
| Mrs Mariza Gabriela Oliveira Sousa Cardoso | Birmingham | United Kingdom | Associate | View | |
| Miss Katherine OLIPHANT | Tarragona | Spain | CL (Translator) | Member | View |
| Ms Lachesis Olegario Braick | London | United Kingdom | CL (Translator) | Member | View |
| Ms Pamela OLEA | Wokingham | United Kingdom | Member | View | |
| Mr Kenneth OLDFIELD | Oldham | United Kingdom | Member | View |