Bert, Bertie, Berto, Bertus (also short for Albert)
Beto, Betinho (Portuguese)
Bo, Bob, Bobbie, Bobby
Dobbie, Dobby
Hob, Hopkin (Medieval English)
Hopcyn (Welsh)
Hrodebert, Hrodpreht (Old High German)
Nobby (also short for Norbert)
Rab, Rabbie (Scots)
Raibeart (Scottish Gaelic)
Rhobert (Welsh)
Roibeárd (Irish)
Rob, Robb, Robbie, Robby (also short for Robin)
Robbe (Dutch, Frisian and Low German short form)
Roban
Robban (Swedish)
Robbert (Dutch)
Robbi (Icelandic)
Robercik or Robuś (Polish, "Little Robert")
Robere (Old French)
Ροβῆρος, Rovēros (Greek)
Róbert (Hungarian, Icelandic, Slovak)
Robertas (Lithuanian)
Roberto (Italian, Portuguese, Spanish)
Robertino (Italian, "Little Robert")
Robertinho (Portuguese, "Little Robert")
Ροβέρτος, Rovértos (Greek)
Roberts (Latvian)
Robertson (English given name)
Robertus (Latin)
Robetus (Medieval misspelling?)
Robi (Croatian, Hungarian, Romanian, Serbian)
Röbi (Swiss German)

Robin (Medieval diminutive in English, Dutch, Swedish)
Robo
Robrecht (Old Dutch)
Rochbert
Rodbeard, Rodbeart
Rodbert, Rodebert, Rotbert, Roteberht, Rotebert (Germanic)
Rodbertus, Rodepertus (Latin)
Rodebrecht (Old German)
Röpke (Low German diminutive form)
Rotbryht (Old English)
Rothbert
Roopertti, Pertti, Roope (Finnish)
Ropars, Ropartz, Roparzh (Breton)
Roupen (Armenian)
Rubert, Ruby (Old Dutch)
Rudebet, Rudbert
Rupert (Dutch, English, German, Polish)
Ruperto (Spanish)
Rupertus, Rvpertvs (Latin)
Ruppert, Ruprecht (Upper German)
Trebor (reversal)