The Obol denomination
The Obol was a form of ancient Greek currency and weight. Originally a small metal spit, six obols constituted a Drachm - a 'handful'.

Depending on the standard used, and obol weighed between 0.44 grams (Achaean) and 0,72 grams (Attic).
Obol

(1) Artaxerxes (Ardashir) II 50-1 BC
Obverse: bust left, wearing diadem and Persepolitan crown with stepped battlements
Reverse: king standing left, holding sceptre; lit altar to left
Ref: Alram 577
(2) Abdera 473-448 BC
Obverse: seated griffin left rising leg
Reverse: quadripartite incuse square
Ref: May 191; SNG Cop. 312 ff.
(3) Abydos (Troas) 480-450 BC
Obverse: eagle left, star above; ABY
Reverse: facing head of Medusa within incuse square
Ref: SNG Copenhagen 5; BMC 4-5
(4) Alexander III 325-300? BC
AR Obol Unknown mint
Obverse: Head of young Herakles right, wearing lion's skin
Reverse: Zeus seated left, leaning on scepter, holding eagle AΛEΞANΔPOY
Ref: None provided
(5) Aspendos c. 465-430 BC
Obverse: Amphora
Reverse: triskeles, pellet; E_Σ
Ref: SNG France 14; SNG von Aulock 4485;...
(6) Assos c. 479-450 BC
Obverse: gryffin right
Reverse: lion head right
Ref: BMC Troas p. 36, 3; Weber 5318; SGC...
(7) Cilician Satrapy c. 379-372 BC
Obverse: Female head (Aphrodite?) facing left, wearing wreath of reeds, earring and necklace of pearls/beads
Reverse: Female head facing forwards, wearing stephane (headdress) and pearl/beaded necklace
Ref: Imhoof-Blumer 1
(8) Eukratides I 171-145 BCE
Obverse: Diademed bust of king right
Reverse: Diademed bust of king right Rev.: ΒΑΣΙΛΕΩΣ ΕΥΚΡΑΤΙΔΟΥ (Two pilei surmounted by stars and two palm branches), monogram in field
Ref: HGCS 12/138
(9) Evagoras I 411-373 BC
Obverse: Bare head of young male facing right (Evagoras?)
Reverse: Smooth, no design
Ref: BMC 45; Tziambazis 116
(10) Hadrian 126-127 AD
Obverse: laureate bust right, draped shoulder; AVT KAI_TPAI AΔPIA CEB
Reverse: two cornucopiaes; L IA
Ref: Köln 961; Dattari (Savio) 1915; K&G...
(11) Kebren c. 500-400 BC
Obverse: head of Apollo left
Reverse: ram head left within incuse square
Ref: SNG Ashmolean 1086 (diobol); SNGvA ...
(12) Kherei 440-410 BC
Obverse: Helmeted head of Athena left
Reverse: Head of Kherei right, wearing bashlyk, in pelleted round border within incuse circle.
Ref: Falghera -; SNG Copenhagen Suppl. -...
(13) Kos 500-480 BC
Obverse: crab
Reverse: quadripartite incuse square
Ref: SNG Copenhagen 615-6 (diobols); HGC...
(14) Laranda Circa 324-323 BC
Obverse: Baaltars seated left holding long scepter, bunch of grapes and ear of grain
Reverse: Forepart of wolf right; inverted crescent above; all within circle of pellets.
Ref: Göktürk 82; SNG France 443
(15) Laranda c. 400-300 BC
Obverse: Baal seated left, stalk of grain and bunch of grapes in right hand, long scepter vertical behind in left hand
Reverse: wolf forepart right, crescent above
Ref: SNG BnF 450 (uncertain Cilicia), SN...
(16) M. Aemilius Lepidus 44-42 BC
AR Obol Cabellio
Obverse: Head of Apollo right; CABE upwards in right field.
Reverse: LE-PI flanking cornucopia; all within laurel wreath
Ref: RPC I 528
(17) Mazaios 361/0-334 BC
Obverse: Baal seated left, holding grapes, grain ear, and sceptre
Reverse: lion attacking stag left
Ref: Casabonne Series 1; SNG France 329;...
(18) Miletos 520-500 BC
Obverse: head of lion left
Reverse: star ornament within incuse square
Ref: Pfeiler, 6; SNG von Aulock 2080; BM...
(19) Miletos 520-500 BC
Obverse: head of lion left
Reverse: star ornament within incuse square
Ref: Grose 8210, SNGvA 2081, SNG Cop 944...
(20) Neandreia c. 410-370 BC
Obverse: laureate head of Apollo right
Reverse: ram right; NEA / N
Ref: SNG Cop 446; SNGvA 7628; SNG Munche...
(21) Pantikapaion 300-200 BC
Obverse: Head of beardless Pan left, wreathed with ivy and grapes strung
Reverse: Bow and arrow; ΠAN (eight-rayed star countermark from undertype)
Ref: SNG Pushkin 956 (same undertype w/c...
(22) Pharkadon 480 - 400 BC
Obverse: Horse prancing right
Reverse: ΦΑΡ-ΚΑΔO, Athena standing right, holding spear and shield; all within incuse square.
Ref: BCD Thessaly I 1271 var. (ethnic), ...
(23) Ptolemy II 264-256 BC
Obverse: head of Alexander III right wearing elephant scalp headdress and aegis
Reverse: eagle standing on lightning left, spread wings; ΠTOΛEMAIOY_ΒAΣIΛEΩΣ / E
Ref: Svornos 450
(24) Ptolemy II 264-256 BC
Obverse: head of Alexander III right wearing elephant scalp headdress and aegis
Reverse: eagle standing on lightning left, spread wings; ΠTOΛEMAIOY_ΒAΣIΛEΩΣ / A
Ref: Svornos 424
(25) Selge 350-300 BC
Obverse: Facing gorgoneion
Reverse: Helmeted head of Athena right; astralagos behind
Ref: SNG France 1934
(26) Selge 250-190 BC
Obverse: Facing gorgoneion
Reverse: Helmeted head of Athena right within incuse square
Ref: SNG von Aulock 5242
(27) Selge c. 350-300 BC
Obverse: facing head of Medusa (Gorgoneion), tongue protruding
Reverse: head of Athena leftwearing crested helmet; astragalos behind
Ref: SNG BnF 1928; SNGvA 5281; BMC Lycia...
(28) Side c. 400-300 BC
Obverse: lion head right
Reverse: helmeted head of Athena right
Ref: Atlan, Side 77 (dies Exemplar); SNG...
(29) Sogdiana c. 300-500 AD
Obverse: head left
Reverse: archer right holding bow and arrow
Ref: Mitch., Central Asia, 16; Mitch., I...
(30) Tanagra 387-374 BC
Obverse: boeotian shield
Reverse: forepart of horse right; TA
Ref: BCD Boiotia 280; SNG Copenhagen 231
(31) Tarsos 379-362 BC
Obverse: Head of Nymph? facing slightly left wearing earrings and necklace
Reverse: Bearded head of Ares? left wearing crested Attic style helmet
Ref: SNG France 303ff var.; SNG Levante ...
(32) Uvug 470-440 BC
Obverse: Forepart of winged human-headed bull right
Reverse: Male? head right; OFOV (Uvug) within incuse square
Ref: Babelon, Traité, 315 ff var.; SNG v...