In the last few days I have worked on finding the haplogroups of the clan chiefs of Scottish clans. Almost all of them have extensive surname DNA projects, so it was easy in most cases. The list includes most of the peerage of Scotland from Viscount to Duke. Highland clans belonging to R1b-L21 generally do not have aristocratic titles (with the notable exception of the Campbell and Drummond chiefs).
You will notice that Clan Douglas is absent. This is because of conflicting data. Only one member reported to descend from the Douglas-Hamilton (Dukes of Hamilton), but his haplogroup is I2a1a-L1193. However Clan Douglas supposedly descend from the same ancestor as clans Murray and Sutherland, which would mean R1b-DF27>BY67446, and indeed many Douglas do. This either means that the I2a1a participant is not who is says he is, or a non-paternity event happened somewhere. As we have no idea of where, I did not list the Douglas chiefs for the time being.

You will notice that Clan Douglas is absent. This is because of conflicting data. Only one member reported to descend from the Douglas-Hamilton (Dukes of Hamilton), but his haplogroup is I2a1a-L1193. However Clan Douglas supposedly descend from the same ancestor as clans Murray and Sutherland, which would mean R1b-DF27>BY67446, and indeed many Douglas do. This either means that the I2a1a participant is not who is says he is, or a non-paternity event happened somewhere. As we have no idea of where, I did not list the Douglas chiefs for the time being.