The McQuillan Clan Association accepts any of the known spellings of the McQuillan surname:
| MacQuillan | MacQuilland | MacQuillen | MacQuillian | MacQuillin | MacQuillion | |
| MacQuillon | MacQuilly | MacWillie | McQueelan | McQueelin | McQuelan | |
| McQueland | McQuelian | McQuelin | McQuellan | McQuelland | McQuill | |
| McQuillan | McQuilland | McQuillen | McQuillian | McQuillin | McQuillion | |
| McQuillon | Quillan | Quillen | Quillin |
The following surnames are usually distinct clan names, but can occasionally represent a "hidden" derivation from a McQuillan surname. Bearers of these names may be accepted into the association where a relationship is shown to one of the McQuillan surnames, or may wish to become associate members if such a relationship is suspected but not yet demonstrated:
| Campbell | Cullen | Killen | MacAilan | MacCaillan | MacCaillion | |
| MacCullen | MacKillan | MacKillian | MacKillon | McAilin | McAyland | |
| McKillan | McKillin | McKillion | McKillon | McWilliam | McWilliams | |
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