Greek philosopher no relation scholarch of the Platonic Academy
Speusippus (; Greek: Σπεύσιππος; c. 408 – 339/8 BC) was an ancient Greek philosopher. Speusippus was Plato's nephew by his sister Potone.  After Plato's death, c. 348 BC, Speusippus inherited the Academy, near age 60, and remained its head for the next eight years. However, following a stroke, he passed the chair to Xenocrates. Although the successor to Plato in the Academy, Speusippus frequently diverged from Plato's teachings. He rejected Plato's Theory of Forms, and whereas Plato had identified the Good with the ultimate principle, Speusippus maintained that the Good was merely secondary. He also argued that it is impossible to have satisfactory knowledge of any thing without knowing all the differences by which it is separated from everything else.
The standard edition of the surviving fragments and testimonies is Leonardo Tarán's Speusippus of Athens: A Critical Study with a Collection of the Related Texts and Commentary (1982).Life
Speusippus was a native of Athens, and the son of Eurymedon and Potone, a sister of Plato, he belonged to the deme of Myrrhinus. The pseudonymous Thirteenth Letter of Plato claims that Speusippus married his niece (his mother's granddaughter). We hear nothing of his life until the time when he accompanied his uncle Plato on his third journey to Syracuse (Italy), where he displayed considerable ability and prudence, especially in his amicable relations with Dion. His moral worth is recognised even by Timon, though only that he may heap the more unsparing ridicule on his intellect.The report about his sudden fits of anger, his greed, and his debauchery, are probably derived from a very impure source: Athenaeus and Diogenes Laërtius can adduce as authority for them scarcely anything more than the abuse in some spurious letters of Dionysius the Younger, who was banished by Dion, with the cooperation of Speusippus. Having been selected by Plato as his successor as the leader (scholarch) of the Academy, he was at the head of the school for only eight years (348/7–339/8 BC). He died, it appears, of a lingering paralytic illness, presumably a stroke. He was succeeded as the head of the school by Xenocrates.
no relation