Thanks, Paul. Intertwined family trees are just my thing.
These people all have something named after them.
But (just to make it more of a challenge) each of them is better known by another title or surname, and (with one exception) it's the more familiar form that has lent itself to the item.
One point for each correct item, and bonus points for an explanation of why it was named after that person and/or cool details.
1. Harald I of Denmark (c910–985) -
Bluetooth. Harald was nicknamed "Bluetooth". He brought various Scandinavian territories together. Bilbo, 1 point; Kumabjorn 1 point.
2. Alice Longworth (1884–1980)
3. James Thomas Brudenell (1797-1868) -
Cardigan. The OED simply states that the cardigan (at that time a knitted wool waistcoat) was named for the Earl of Cardigan, "distinguished in the Crimean war". Bilbo, 2 points.
4. Jeanne Antoinette Poisson (1721-1764) - the
Pompadour hairstyle associated with Madame de Pompadour. Poohbear, 2 points.
5. FitzRoy James Henry Somerset (1788–1855) - the
Raglan sleeve. Bilbo, 1 point.