"no matter who" is the same as "whoever", but is more limited in use. whoever - 1. any person who; anyone that; "whoever wants it can have it" 2. no matter who; "I'll come tomorrow, whoever may be here" 3. an intensive form of who, used in questions; "whoever could have thought that?" 4. an unknown or unspecified person; "give those to John, or Cathy, or whoever"