I started running a campaign last night, had two clerics booked to help out the party. One said he wanted to play an "Undead Slayer". Fine. Second player said he wanted to play an Undead Lord. Uh-oh. I decided not to turn him down outright but warned him about the first cleric - this put me in a little bit of an awkward position, since I don't want to tell characters what they can play, but also don't want to encourage PVP before the first session.
So what happened? Undead Slayer was a no-show. (I was hesitant to ban archetypes on behalf of someone I've never met, and I guess I was right).
Undead Lord, meanwhile, acted like the dedicated healer. Used all his spells to heal people (going to have a chat with him about how spontaneous casting works), and then pulled a weird one-two to use negative channeling to heal a downed party member (started a rules thread about it).
His character concept is pretty intriguing, and I want to let him act as the healer AND keep his undead portfolio. To that end, I drafted an email offering to let him change his deity from Urgothoa to Shyka, and said that I'd handwave Undead as one of Shyka's subdomains, so that he could take Variant Channeling (with the intent to let first level opposed channeling of the opposite type heal/harm for 1d3). This isn't Golarion, after all, but a homebrew setting.
But now... I don't know. Soon as I drafted the letter, it started to feel like I'm letting somebody have their cake and eat it, too. I looked around and couldn't find one Golarion deity that offers the undead subdomain that WASN'T evil. Is there a good reason for this? Does letting PCs have undead pets break your game?
I should add the group isn't full of evil characters. One character is playing a ninja assassin, but he couldn't even make it to the first session (influenza). Since the character has yet to be introduced, I think I might work with the player to soften that "assassin" edge down a bit (like, he has yet to make his first kill).
Undeath is, in Golarion, always evil. There are exceptions out there, but JJ has indicated that these were oversights. If a lawful good character were to be turned into an undead, even a sentient undead, their alignment would automatically be changed to some variety of evil.
A non-Golarion setting can be different, of course.
Mechanically, I don't see a problem.
From a roleplaying perspective, it can be interesting. If the party doesn't have a problem with it, neither should you (but that obviously doesn't mean your NPCs necessarily won't!).
An LE or NE Undead Lord would be entirely content with traveling with a party full of non-Evil players, using their powers to further their own goals. However, if the rest of the party isn't okay with it, THEN there's a problem. That's something for you and your players to discuss, though.
I looked around and couldn't find one Golarion deity that offers the undead subdomain that WASN'T evil.
Option 1: Allow agnostic (atheist?) clerics. Clerics who dedicate themselves to a divine concept worthy of devotion free of a deific abstraction. Clerics always have a deity in Golarion, but it's an option for a non-Golarion campaign.
Option 2: Don't make the Undead subdomain available in the campaign.
Result: Player takes the Death domain instead. This opens up the following non-evil deities: Ancestral Spirits, Fandarra, Hanspur, Pharasma, and Shyka.
Hanspur is awesome.
Pharasma can work if you consider the companion to be a soul that has been judged in the boneyard, and allowed to return as penance or to correct a terrible wrong. Pharasma has allowed souls to return before, to pass along important messages, or even as haunts. So 'sanctioned' undead, which are powered by souls that have passed judgement, don't corrupt the souls natural journey, so it should be OK. (The church of course doesn't see it this way) She wouldn't want you casting animate dead and stuff, but there's a Pharasma-friendly variant Death domain here: http://paizo.com/paizo/blog/v5748dyo5lbvp?Golarion-Day-Other-Gods-and-New-S ubdomains