The main source of the story of Mot 'Death' is Ugaritic. He is a son of 'El, and according to instructions given by the god Hadad to his messengers, lives in a city named hmry, a pit is his throne, and Filth is the land of her heritage. But Ba'al warns them:
that you not come near to divine Death, lest he made you like a lamb in his mouth, you both be carried away like a kid in the breach of his windpipe.
Hadad seems to be urging that Mot come to his feast and submit himself to Hadad. Death sends back a message that his appetite is that of lions in the wilderness, like the longing of dolphins in the sea and he threatens to devour Ba'al himself. In a subsequent passage Death seemingly makes good his threat, or at least is deceived into believing he has slain Ba'al. Numerous gaps in the text make this portion of the tale obscure. The sun stops shining as its goddess Shapash joins Ba'al's sister 'Anat in burying him. 'Anat then comes upon Mot, seizing him, splitting him with a blade, winnowing him in a sieve, burning him in a fire, grinding him under a millstone, and throwing what remains in the end over a field for birds to devour. El, Baal's father, dreams that Baal is alive, and sends Shapash to bring him back to life because the land had become dry. After seven years, Death returns, seeking vengeance and demanding one of Ba'al's brothers to feed upon. A gap in the text is followed by Mot complaining that Ba'al has given Mot his own brothers to eat, the sons of his mother to consume. A single combat between the two breaks out until the sun goddess Shapash upbraids Mot, informing him that his own father El will turn against him and overturn his throne if he continues. Mot concedes and the conflict ends.
Phoenician sources
A Phoenician account survives in a paraphrase of the Greek author Philo of Byblos by Eusebius, who writes of a Phoenician historian named Sanchuniathon. In this account Death is a son of 'El and counted as a god, as the text says in speaking of 'El/Cronus:
And not long after another of his sons by Rhea, named Muth, having died, he deifies him, and the Phoenicians call him Thanatos and Pluto.
But earlier in a philosophical creation myth Sanchuniathon has referred to great wind which merged with its parents and that connection was called 'Desire' :
From its connection Mot was produced, which some say is mud, and others a putrescence of watery compound; and out of this came every germ of creation, and the generation of the universe. So there were certain animals which had no sensation, and out of them grew intelligent animals, and were called "Zophasemin", that is "observers of heaven"; and they were formed like the shape of an egg. Also Mot burst forth into light, and sun, and moon, and stars, and the great constellations.
The form Mot here is not the same as Muth which appears later.
In Hebrew scriptures, Death is sometimes personified as a devil or angel of death. In both the Book of Hosea and the Book of Jeremiah, Maweth/Mot is mentioned as a deity to whom Yahweh can turn over Judah as punishment for worshiping other gods.