 The goal of the first part is to find the highest tolerable dose of ONC201 that can be given to patients with relapsed or refractory MCL, DLBCL, and TLCL. Groups of subjects will receive increasing doses of ONC201 by mouth on day 1 of each 21 days cycle or on Day 1 of every week until there are side effects that are not tolerated or a maximum of 625 mg has been found to be tolerable. 