I really liked this Necromancer re-do from the DM's Guild. It's not mine, but I did pay the author for it.
An Updated View On Necromancy - When this was first written in 2017, I would not have expected Xanathar's and Tasha's to resolve a simple longstanding i
www.dmsguild.com
It includes a 1st level Undead Servitude spell that creates an undead familiar. The familiar consumes a spell slot while animated, with the spell slot letting you scale up to higher level creatures. At 1st level you're looking at an undead Commoner... but it's still an undead at 1st level.
With 3rd level spells your familiar can be a CR 1/4 base creature like a giant wolf spider or troglodyte, 6th level spells get you an undead ogre, and if you give up your 9th level slot you've got a pet undead young dragon.
Your one undead minion acts on its own initiative and turn in combat... but there's only one, and it's never more powerful than the party fighter.
It's my official "This is a Necromancer" in my games now, replacing the PHB version.