Helm is the God of Guardians. He is Lawful Neutral. He is only one of many, though. He serves Tyr, the God of Justice, who is Lawful Good.
Paladins can serve gods that are up to one alignment step away from lawful good (which they have to be), which means they can serve deities that are either lawful good, neutral good or lawful neutral. The exception to this are Paladins of the Firehair (Sune) who worship a deity that is chaotic good).
Common paladin orders of Faerun include:
Paladins of the High One - Azuth
Paladins of the Grain Goddess - Chauntea
Paladins of the Watcher - Helm
Paladins of the Crying God - Ilmater
Paladins of the Lord of the Dead - Kelemvor
Paladins of the Morninglord - Lathander
Paladins of the Firehair - Sune
Paladins of the Loyal Fury - Torm
Paladins of the Just God - Tyr
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