Gillebrigde?

Gillebride, or Gilbert, who is mentioned by the oldest Highland genealogist as "rig eilean Shidir," that is, King of the Sudereys or Southern Isles. His daughter was the wife of Wymund MacHeth, Earl of Moray. He was called Gillebride na h-Uamh, from the fact that during a certain period of his depressed fortunes he lived in a cave in the district of Morvern.
From Gillebride are said to have descended besides the Clan Donald and Clan Dougall, etc. the Maclachlans, MacEwin of Otter, and others. His son was Somerled rex insularum, or, as he is known in Highland tradition, Somhairle Mor MacGillebhride.

Source: "The Clan Donald" Vol 3, page 178.

GilleBride, of royal Irish ancestry possible Father of Somerled See Discussion: https://www.geni.com/discussions/220567

cf "Brother [and sister], parents not known: SOMERLED" http://fmg.ac/Projects/MedLands/SCOTTISH%20NOBILITY.htm#Reginaldson...

cf "Somerled, a Celtic chief" http://fmg.ac/Projects/MedLands/SCOTTISH%20NOBILITY.htm#Reginaldson...

cf His father, GilleBride, of royal Irish ancestry [no sources cited] https://en.wikipedia.org/wiki/Somerled

Some sleuthing by Anne Brannen (See Discussions) Edinburgh University MS 1467, in the first part, written by Dubhghall Albanach, is quoted in “1467 MS: The MacNeils”, published in West Highland Notes & Queries, ser. 4, no. 6 (Feb. 2018), pp. 3–25 --

this is footnote 25:

"Dubhghall Albanach gives two variants of Somerled’s pedigree on the same page. In one (1vbc23–24) he is somairle mac gilla brigde mhic gofraigh mhic alasdair mhoir. In the other (1vd9–12) he is somairle mac gillebrigde mhic gillaeaghanain mhic solaim. This underlines his status as a popular hero who sprang from obscurity."

so -- the discrepancy here is in his grandfather; in both cases his father is Gillebrigde.

Now, the manuscript is not contemporary, having been copied from earlier sources in 1467 (this date appears in the manuscript itself; it was earlier dated at c1450).

But it looks like having Gillebrigde as his father isn't an enormous problem. Is is true? We don't know. But there is some medieval evidence for the name of his father. Where THAT evidence comes from we don't know. There's no contemporary evidence.