| | Multidisciplinary Technologies | 3696 |
| | Chemical and Pharmaceutical Sciences | 4876 |
| | Dublin Institute of Technology | 4673 |
| | Campus Planning Office | 8057 |
| | Research & Enterprise | 2205105 |
| | Research and Enterprise | 7511 |
| | Retail and Services Management | 3002 |
| | Architecture & Urban Design | 3948 |
| | College of Engineering & Built Environment | 3650 |
| | Hospitality Management and Tourism | 4398 |
| O'Brien, Tony | Construction Skills | 3897 |
| | Research and Enterprise | 3442 |
| | Retail and Services Management | 7062 |
| | Mechanical and Transport Engineering | 2967 |
| O'Callaghan, Orla | Architecture & Urban Design | 8784024 |
| | National Optometry Centre | 4751 |
| | Real Estate and Construction Economics | 3865 |
| | Electrical and Electronic Engineering | 2807 |
| | Hothouse Knowledge Transfer Office City Campus | 3111 |
| | Accounting and Finance | 3232 |
| | Campus Services & Relocation | 3354 |
| | Campus Services & Relocation | 2205099 |
| O'Connor, Anthony | Mechanical and Transport Engineering | 3809 |
| | School of Creative Arts | 4246 |
| | Food Science & Env. Health | 4455 |
| | Hospitality Management and Tourism | 7585 |
| O'Connor, David | Chemical and Pharmaceutical Sciences | 4571 |
| | Environmental Planning and Management | 3803 |
| | Food Science & Env. Health | 7550 |
| | Financial Aid & Accommodation Services | 2205017 |
| O'Connor, James | Construction Management & Technology | 3886 |
| | Culinary Arts and Food Technology | 4435 |
| | Disability Support Service | 7656 |
| | Disability Support Service | 2205097 |
| | Dublin Institute of Technology | 3962 |
| O'Connor, Tony | Sports | 0876114055 |
| | Chemical and Pharmaceutical Sciences | 2861 |
| | Civil and Structural Engineering | 2913 |
| | Retail and Services Management | 7012 |
| | Technological University Programme Team | 0868211031 |
| O'Donoghue, Donnacha | Hospitality Management and Tourism | 7547 |
| | Chemical and Pharmaceutical Sciences | 4775 |
| | Chemical and Pharmaceutical Sciences | 4766 |
| | Civil and Structural Engineering | 3711 |
| | Electrical and Electronic Engineering | 4796 |
| | Electrical and Electronic Engineering | 4875 |
| | Dublin Institute of Technology | |
| | Electrical and Electronic Engineering | 4772 |
| O'Flaherty, Micheal | Civil & Building Services Engineering | 3830 |
| | Electrical and Electronic Engineering | 4962 |
| O'Hanlon, Tracy | Maintenance | 3607 |
| | Hospitality Management and Tourism | 4234 |
| | Civil and Structural Engineering | 3907 |
| | Learning Teaching & Technology Centre | 7872 |
| | Technological University for Dublin | 4236 |
| | Dublin Institute of Technology | 4718 |
| | Hospitality Management and Tourism | 4465 |
| | Accounting and Finance | 7192 |
| O'Leary, Vincent | Print and Digital Media | 3772 |
| | Accounting and Finance | 3231 |
| O'Meara, Finbarr | Electrical and Electronic Engineering | 4722 |
| | Disability Support Service | 0861744955 |
| | Retail and Services Management | 7003 |
| | Mechanical and Transport Engineering | 3789 |
| O'Neill, Mandy | Photography | 6752618 |
| | Languages Law and Social Sciences | 4466 |
| O'Neill, Maurice | Physics | 4813 |
| | Quality Assurance | 2205078 |
| | Civil & Building Services Engineering | 3909 |
| | Hospitality Management and Tourism | 4469 |
| | Accounting and Finance | 7175 |
| | Hothouse Knowledge Office City Campus | 5330 |
| | Languages Law and Social Sciences | 7580 |
| | Retail and Services Management | 7044 |
| | Real Estate and Construction Economics | 3739 |
| | International Office | 4253 |
| | Accounting and Finance | 3226 |
| | Electrical and Electronic Engineering | 2801 |
| O'Rourke, Brendan | Dublin Institute of Technology | 7097 |
| O'Rourke, Fergal | Engineering | 2978 |
| | Digital Campus & Learning Transformation | 7860 |
| | Mechanical and Design Engineering | 3847 |
| | Languages Law and Social Sciences | 4644 |
| O'Shea, Anthony | Focas | 7973 |
| O'Shea, Denis | Tourism & Food | 4508 |
| O'Shea, Kevin Cornelius | Art Design and Printing | 8550466 |
| | Chemical and Pharmaceutical Sciences | 4956 |
| | Hospitality Management and Tourism | 7592 |
| | Mathematical Sciences | 4823 |
| O'Sullivan, Vincent | Maintenance | 3607 |
| | Languages Law and Social Sciences | 4522 |
| | Mechanical and Design Engineering | 2915 |
| | Languages Law and Social Sciences | 4552 |
| Olwill, Ronan | Construction | 4756911 |
| Onyejelem, Chinedu Nnadozie | Media | 4508 |
| Operator, Switch | Telephone Services | 3000 |
| | Civil & Structural Engineering | 3840 |
| Overnight Experiments Rooms | | 7999286 |
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